diff --git a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/Assert.scala b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/Assert.scala
index 7b5b2df74..4ec63bee4 100644
--- a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/Assert.scala
+++ b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/Assert.scala
@@ -31,11 +31,18 @@ trait Assert extends js.Object {
   def deepStrictEqual(actual: js.Any, expected: js.Any, message: String): Unit = js.native
   def deepStrictEqual(actual: js.Any, expected: js.Any): Unit                  = js.native
 
-  def doesNotReject(asyncFn: js.Function | js.Promise[_], error: js.RegExp | js.Function, message: String): Unit =
-    js.native
-  def doesNotReject(asyncFn: js.Function | js.Promise[_], error: js.RegExp | js.Function): Unit = js.native
-  def doesNotReject(asyncFn: js.Function | js.Promise[_], message: String): Unit                = js.native
-  def doesNotReject(asyncFn: js.Function | js.Promise[_]): Unit                                 = js.native
+  def doesNotReject(asyncFn: js.Function, error: js.RegExp, message: String): Unit     = js.native
+  def doesNotReject(asyncFn: js.Function, error: js.RegExp): Unit                      = js.native
+  def doesNotReject(asyncFn: js.Function, error: js.Function, message: String): Unit   = js.native
+  def doesNotReject(asyncFn: js.Function, error: js.Function): Unit                    = js.native
+  def doesNotReject(asyncFn: js.Function, message: String): Unit                       = js.native
+  def doesNotReject(asyncFn: js.Function): Unit                                        = js.native
+  def doesNotReject(asyncFn: js.Promise[_], error: js.RegExp, message: String): Unit   = js.native
+  def doesNotReject(asyncFn: js.Promise[_], error: js.RegExp): Unit                    = js.native
+  def doesNotReject(asyncFn: js.Promise[_], error: js.Function, message: String): Unit = js.native
+  def doesNotReject(asyncFn: js.Promise[_], error: js.Function): Unit                  = js.native
+  def doesNotReject(asyncFn: js.Promise[_], message: String): Unit                     = js.native
+  def doesNotReject(asyncFn: js.Promise[_]): Unit                                      = js.native
 
   /**
     * Asserts that the function block does not throw an error. See assert.throws() for more details.
@@ -44,10 +51,12 @@ trait Assert extends js.Object {
     * error is of a different type, or if the error parameter is undefined, the error is propagated back to the caller.
     * @example assert.doesNotThrow(block[, error][, message])
     */
-  def doesNotThrow(block: js.Function, error: js.RegExp | js.Function, message: String): Unit = js.native
-  def doesNotThrow(block: js.Function, error: js.RegExp | js.Function): Unit                  = js.native
-  def doesNotThrow(block: js.Function, message: String): Unit                                 = js.native
-  def doesNotThrow(block: js.Function): Unit                                                  = js.native
+  def doesNotThrow(block: js.Function, error: js.RegExp, message: String): Unit   = js.native
+  def doesNotThrow(block: js.Function, error: js.RegExp): Unit                    = js.native
+  def doesNotThrow(block: js.Function, error: js.Function, message: String): Unit = js.native
+  def doesNotThrow(block: js.Function, error: js.Function): Unit                  = js.native
+  def doesNotThrow(block: js.Function, message: String): Unit                     = js.native
+  def doesNotThrow(block: js.Function): Unit                                      = js.native
 
   /**
     * @see https://nodejs.org/api/assert.html#assert_assert_fail_message
@@ -102,17 +111,17 @@ trait Assert extends js.Object {
     * of the message parameter. If the message parameter is undefined, a default error message is assigned.
     * @example assert.throws(block[, error][, message])
     */
-  def throws(block: js.Function, error: js.RegExp | js.Function | js.Object | Error, message: String): Unit = js.native
-  def throws(block: js.Function, error: js.RegExp | js.Function | js.Object | Error): Unit                  = js.native
-
-  def rejects(asyncFn: js.Function | js.Promise[_],
-              error: js.RegExp | js.Function | js.Object | Error,
-              message: String
-  ): Unit = js.native
-  def rejects(asyncFn: js.Function | js.Promise[_], error: js.RegExp | js.Function | js.Object | Error): Unit =
-    js.native
-  def rejects(asyncFn: js.Function | js.Promise[_], message: String): Unit = js.native
-  def rejects(asyncFn: js.Function | js.Promise[_]): Unit                  = js.native
+  def throws(block: js.Function, error: js.Object, message: String): Unit = js.native
+  def throws(block: js.Function, error: js.Object): Unit                  = js.native
+
+  def rejects(asyncFn: js.Function, error: js.Object, message: String): Unit   = js.native
+  def rejects(asyncFn: js.Function, error: js.Object): Unit                    = js.native
+  def rejects(asyncFn: js.Function, message: String): Unit                     = js.native
+  def rejects(asyncFn: js.Function): Unit                                      = js.native
+  def rejects(asyncFn: js.Promise[_], error: js.Object, message: String): Unit = js.native
+  def rejects(asyncFn: js.Promise[_], error: js.Object): Unit                  = js.native
+  def rejects(asyncFn: js.Promise[_], message: String): Unit                   = js.native
+  def rejects(asyncFn: js.Promise[_]): Unit                                    = js.native
 }
 
 /**
diff --git a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/StringDecoder.scala b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/StringDecoder.scala
index 2597b0aa1..b78c311df 100644
--- a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/StringDecoder.scala
+++ b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/StringDecoder.scala
@@ -20,12 +20,14 @@ class StringDecoder(encoding: String) extends IEventEmitter {
     * Returns any trailing bytes that were left in the buffer.
     * @example decoder.end()
     */
-  def end(buffer: TypedArray[_, _] | DataView): String = js.native
-  def end(): String                                    = js.native
+  def end(buffer: TypedArray[_, _]): String = js.native
+  def end(buffer: DataView): String         = js.native
+  def end(): String                         = js.native
 
   /**
     * Returns a decoded string.
     * @example decoder.write(buffer)
     */
-  def write(buffer: TypedArray[_, _] | DataView): String = js.native
+  def write(buffer: TypedArray[_, _]): String = js.native
+  def write(buffer: DataView): String         = js.native
 }
diff --git a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/buffer/Buffer.scala b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/buffer/Buffer.scala
index 123474086..9bb674d90 100644
--- a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/buffer/Buffer.scala
+++ b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/buffer/Buffer.scala
@@ -97,49 +97,36 @@ class Buffer private[this] () extends Uint8Array( /* dummy to trick constructor
     */
   def equals(otherBuffer: Uint8Array): Boolean = js.native
 
-  /**
-    * Fills buf with the specified value. If the offset and end are not given, the entire buf will be filled.
-    * This is meant to be a small simplification to allow the creation and filling of a Buffer to be done on a single line.
-    *
-    * @param value    The value to fill buf with
-    * @param offset   Where to start filling buf. Default: 0
-    * @param end      Where to stop filling buf (not inclusive). Default: buf.length
-    * @param encoding If value is a string, this is its encoding. Default: 'utf8'
-    * @return A reference to buf
-    * @see https://nodejs.org/api/buffer.html#buffer_buf_fill_value_offset_end_encoding
-    */
-  def fill(value: Uint8Array | Int | String, offset: Int, end: Int, encoding: String): this.type = js.native
-  def fill(value: Uint8Array | Int | String, offset: Int, end: Int): this.type                   = js.native
-  def fill(value: Uint8Array | Int | String, offset: Int, encoding: String): this.type           = js.native
-  def fill(value: Uint8Array | Int | String, offset: Int): this.type                             = js.native
-  def fill(value: Uint8Array | Int | String, encoding: String): this.type                        = js.native
-  def fill(value: Uint8Array | Int | String): this.type                                          = js.native
-
-  /**
-    * Returns the index of the first occurrence of value in buf or -1 if buf does not contain value
-    * @param value      What to search for
-    * @param byteOffset Where to begin searching in buf. Default: 0
-    * @param encoding   If value is a string, this is its encoding. Default: 'utf8'
-    * @return The index of the first occurrence of value in buf or -1 if buf does not contain value
-    * @example {{{ buf.indexOf(value[, byteOffset][, encoding]) }}}
-    */
-  def indexOf(value: Buffer | Int | String, byteOffset: Int, encoding: String): Int = js.native
-  def indexOf(value: Buffer | Int | String, byteOffset: Int): Int                   = js.native
-  def indexOf(value: Buffer | Int | String, encoding: String): Int                  = js.native
-  def indexOf(value: Buffer | Int | String): Int                                    = js.native
-
-  /**
-    * Equivalent to buf.indexOf() !== -1.
-    * @param value      What to search for
-    * @param byteOffset Where to begin searching in buf. Default: 0
-    * @param encoding   If value is a string, this is its encoding. Default: 'utf8'
-    * @return true if value was found in buf, false otherwise
-    * @example {{{ buf.includes(value[, byteOffset][, encoding]) }}}
-    */
-  def includes(value: Buffer | Int | String, byteOffset: Int, encoding: String): Boolean = js.native
-  def includes(value: Buffer | Int | String, byteOffset: Int): Boolean                   = js.native
-  def includes(value: Buffer | Int | String, encoding: String): Boolean                  = js.native
-  def includes(value: Buffer | Int | String): Boolean                                    = js.native
+  def fill(value: Uint8Array, offset: Int, end: Int): this.type               = js.native
+  def fill(value: Uint8Array, offset: Int): this.type                         = js.native
+  def fill(value: Uint8Array): this.type                                      = js.native
+  def fill(value: Int, offset: Int, end: Int): this.type                      = js.native
+  def fill(value: Int, offset: Int): this.type                                = js.native
+  def fill(value: Int): this.type                                             = js.native
+  def fill(value: String, offset: Int, end: Int, encoding: String): this.type = js.native
+  def fill(value: String, offset: Int, end: Int): this.type                   = js.native
+  def fill(value: String, offset: Int, encoding: String): this.type           = js.native
+  def fill(value: String, offset: Int): this.type                             = js.native
+  def fill(value: String, encoding: String): this.type                        = js.native
+  def fill(value: String): this.type                                          = js.native
+
+  def indexOf(value: Buffer, byteOffset: Int): Int                   = js.native
+  def indexOf(value: Buffer): Int                                    = js.native
+  def indexOf(value: Int, byteOffset: Int): Int                      = js.native
+  def indexOf(value: Int): Int                                       = js.native
+  def indexOf(value: String, byteOffset: Int, encoding: String): Int = js.native
+  def indexOf(value: String, byteOffset: Int): Int                   = js.native
+  def indexOf(value: String, encoding: String): Int                  = js.native
+  def indexOf(value: String): Int                                    = js.native
+
+  def includes(value: Buffer, byteOffset: Int): Boolean                   = js.native
+  def includes(value: Buffer): Boolean                                    = js.native
+  def includes(value: Int, byteOffset: Int): Boolean                      = js.native
+  def includes(value: Int): Boolean                                       = js.native
+  def includes(value: String, byteOffset: Int, encoding: String): Boolean = js.native
+  def includes(value: String, byteOffset: Int): Boolean                   = js.native
+  def includes(value: String, encoding: String): Boolean                  = js.native
+  def includes(value: String): Boolean                                    = js.native
 
   /**
     * Creates and returns an iterator of buf keys (indices).
@@ -148,18 +135,14 @@ class Buffer private[this] () extends Uint8Array( /* dummy to trick constructor
     */
   def keys(): js.Iterator[Int] = js.native
 
-  /**
-    * Identical to buf.indexOf(), except buf is searched from back to front instead of front to back.
-    * @param value      What to search for
-    * @param byteOffset Where to begin searching in buf. Default: 0
-    * @param encoding   If value is a string, this is its encoding. Default: 'utf8'
-    * @return The index of the last occurrence of value in buf or -1 if buf does not contain value
-    * @example {{{ buf.lastIndexOf(value[, byteOffset][, encoding]) }}}
-    */
-  def lastIndexOf(value: Buffer | Int | String, byteOffset: Int, encoding: String): Int = js.native
-  def lastIndexOf(value: Buffer | Int | String, byteOffset: Int): Int                   = js.native
-  def lastIndexOf(value: Buffer | Int | String, encoding: String): Int                  = js.native
-  def lastIndexOf(value: Buffer | Int | String): Int                                    = js.native
+  def lastIndexOf(value: Buffer, byteOffset: Int): Int                   = js.native
+  def lastIndexOf(value: Buffer): Int                                    = js.native
+  def lastIndexOf(value: Int, byteOffset: Int): Int                      = js.native
+  def lastIndexOf(value: Int): Int                                       = js.native
+  def lastIndexOf(value: String, byteOffset: Int, encoding: String): Int = js.native
+  def lastIndexOf(value: String, byteOffset: Int): Int                   = js.native
+  def lastIndexOf(value: String, encoding: String): Int                  = js.native
+  def lastIndexOf(value: String): Int                                    = js.native
 
   /**
     * Returns the amount of memory allocated for buf in bytes.
@@ -925,8 +908,11 @@ object Buffer extends js.Object {
     *
     * @see [[https://nodejs.org/api/buffer.html#buffer_class_method_buffer_bytelength_string_encoding]]
     */
-  def byteLength(string: String | TypedArray[_, _] | DataView | ArrayBuffer, encoding: String = "utf8"): Int =
-    js.native
+  def byteLength(string: String, encoding: String): Int = js.native
+  def byteLength(string: String): Int                   = js.native
+  def byteLength(string: TypedArray[_, _]): Int         = js.native
+  def byteLength(string: DataView): Int                 = js.native
+  def byteLength(string: ArrayBuffer): Int              = js.native
 
   /**
     * Compares `buf1` to `buf2` typically for the purpose of sorting arrays of `Buffer` instances.
@@ -945,8 +931,8 @@ object Buffer extends js.Object {
     * @see [[https://nodejs.org/api/buffer.html#buffer_class_method_buffer_concat_list_totallength]]
     *
     */
-  def concat(list: js.Array[Buffer] | js.Array[Uint8Array], totalLength: Int): Buffer = js.native
-  def concat(list: js.Array[Buffer] | js.Array[Uint8Array]): Buffer                   = js.native
+  def concat[B <: Uint8Array](list: js.Array[B], totalLength: Int): Buffer = js.native
+  def concat[B <: Uint8Array](list: js.Array[B]): Buffer                   = js.native
 
   /**
     * When passed a reference to the .buffer property of a TypedArray instance, the newly created Buffer
diff --git a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/buffer/package.scala b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/buffer/package.scala
index 8081f0ce4..3c31e7dfd 100644
--- a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/buffer/package.scala
+++ b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/buffer/package.scala
@@ -29,11 +29,9 @@ package object buffer {
     /**
       * Returns the actual byte length of a string. This is not the same as String.prototype.length since that returns
       * the number of characters in a string.
-      *
-      * @param encoding the optional encoding (default "utf8")
       */
     @inline
-    def byteLength(encoding: String = "utf8"): Int = Buffer.byteLength(buffer, encoding)
+    def byteLength(encoding: String): Int = Buffer.byteLength(buffer)
 
     /**
       * Returns the hex-formatted string
diff --git a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/crypto/Certificate.scala b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/crypto/Certificate.scala
index 4393eaacb..0124a7007 100644
--- a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/crypto/Certificate.scala
+++ b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/crypto/Certificate.scala
@@ -9,10 +9,12 @@ import scala.scalajs.js.|
 @js.native
 @JSImport("crypto", "Certificate")
 object Certificate extends js.Object {
-  def exportChallenge(spkac: String | BufferLike): Buffer = js.native
+  def exportChallenge(spkac: String): Buffer     = js.native
+  def exportChallenge(spkac: BufferLike): Buffer = js.native
 
-  def exportPublicKey(spkac: String | BufferLike, encoding: String): Buffer = js.native
-  def exportPublicKey(spkac: String | BufferLike): Buffer                   = js.native
+  def exportPublicKey(spkac: String, encoding: String): Buffer = js.native
+  def exportPublicKey(spkac: String): Buffer                   = js.native
+  def exportPublicKey(spkac: BufferLike): Buffer               = js.native
 
   def verifySpkac(spkac: BufferLike): Boolean = js.native
 }
diff --git a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/crypto/Crypto.scala b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/crypto/Crypto.scala
index 2c3465af5..a3704a58c 100644
--- a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/crypto/Crypto.scala
+++ b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/crypto/Crypto.scala
@@ -49,20 +49,25 @@ trait Crypto extends js.Object {
     *                  either a 'binary' encoded string or a Buffer.
     * @example crypto.createCipher(algorithm, password)
     */
-  @deprecated("Use crypto.createCipheriv() instead.", "Node.js v10.0")
-  def createCipher(algorithm: String, password: Buffer | String): Cipher = js.native
-
-  def createCipheriv(algorithm: String,
-                     key: String | BufferLike,
-                     iv: String | BufferLike,
-                     options: TransformOptions
-  ): Cipher                                                                                        = js.native
-  def createCipheriv(algorithm: String, key: String | BufferLike, iv: String | BufferLike): Cipher = js.native
+  @deprecated("Use crypto.createCipheriv() instead.", "Node.js v10.0") def createCipher(algorithm: String,
+                                                                                        password: Buffer
+  ): Cipher = js.native
+  @deprecated("Use crypto.createCipheriv() instead.", "Node.js v10.0") def createCipher(algorithm: String,
+                                                                                        password: String
+  ): Cipher = js.native
+
+  def createCipheriv(algorithm: String, key: String, iv: String, options: TransformOptions): Cipher     = js.native
+  def createCipheriv(algorithm: String, key: String, iv: BufferLike): Cipher                            = js.native
+  def createCipheriv(algorithm: String, key: BufferLike, iv: String, options: TransformOptions): Cipher = js.native
+  def createCipheriv(algorithm: String, key: BufferLike, iv: BufferLike): Cipher                        = js.native
   @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12)
-  def createCipheriv(algorithm: String, key: KeyObject, iv: String | BufferLike, options: TransformOptions): Cipher =
-    js.native
+  def createCipheriv(algorithm: String, key: KeyObject, iv: String, options: TransformOptions): Cipher = js.native
+  @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12)
+  def createCipheriv(algorithm: String, key: KeyObject, iv: BufferLike, options: TransformOptions): Cipher = js.native
   @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12)
-  def createCipheriv(algorithm: String, key: KeyObject, iv: String | BufferLike): Cipher = js.native
+  def createCipheriv(algorithm: String, key: KeyObject, iv: String): Cipher = js.native
+  @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12)
+  def createCipheriv(algorithm: String, key: KeyObject, iv: BufferLike): Cipher = js.native
 
   /**
     * Creates and returns a Decipher object that uses the given algorithm and password (key).
@@ -75,31 +80,34 @@ trait Crypto extends js.Object {
     * derive a key and IV on their own using crypto.pbkdf2() and to use crypto.createDecipheriv() to create the Decipher object.
     * @example crypto.createDecipher(algorithm, password)
     */
-  @deprecated("Use crypto.createDecipheriv() instead.", "Node.js v10.0")
-  def createDecipher(algorithm: String, password: Buffer | String): Decipher = js.native
-
-  def createDecipheriv(algorithm: String,
-                       key: String | BufferLike,
-                       iv: String | BufferLike,
-                       options: TransformOptions
-  ): Decipher                                                                                          = js.native
-  def createDecipheriv(algorithm: String, key: String | BufferLike, iv: String | BufferLike): Decipher = js.native
-  def createDecipheriv(algorithm: String,
-                       key: KeyObject,
-                       iv: String | BufferLike,
-                       options: TransformOptions
-  ): Decipher                                                                                = js.native
-  def createDecipheriv(algorithm: String, key: KeyObject, iv: String | BufferLike): Decipher = js.native
-
-  def createDiffieHellman(prime: String, primeEncoding: String, generator: Int | BufferLike): DiffieHellman = js.native
+  @deprecated("Use crypto.createDecipheriv() instead.", "Node.js v10.0") def createDecipher(algorithm: String,
+                                                                                            password: Buffer
+  ): Decipher = js.native
+  @deprecated("Use crypto.createDecipheriv() instead.", "Node.js v10.0") def createDecipher(algorithm: String,
+                                                                                            password: String
+  ): Decipher = js.native
+
+  def createDecipheriv(algorithm: String, key: String, iv: String, options: TransformOptions): Decipher     = js.native
+  def createDecipheriv(algorithm: String, key: String, iv: BufferLike, options: TransformOptions): Decipher = js.native
+  def createDecipheriv(algorithm: String, key: BufferLike, iv: String): Decipher                            = js.native
+  def createDecipheriv(algorithm: String, key: BufferLike, iv: BufferLike): Decipher                        = js.native
+  def createDecipheriv(algorithm: String, key: KeyObject, iv: String, options: TransformOptions): Decipher  = js.native
+  def createDecipheriv(algorithm: String, key: KeyObject, iv: BufferLike, options: TransformOptions): Decipher =
+    js.native
+  def createDecipheriv(algorithm: String, key: KeyObject, iv: String): Decipher     = js.native
+  def createDecipheriv(algorithm: String, key: KeyObject, iv: BufferLike): Decipher = js.native
+
+  def createDiffieHellman(prime: String, primeEncoding: String, generator: Int): DiffieHellman        = js.native
+  def createDiffieHellman(prime: String, primeEncoding: String, generator: BufferLike): DiffieHellman = js.native
   def createDiffieHellman(prime: String,
                           primeEncoding: String,
                           generator: String,
                           generatorEncoding: String
   ): DiffieHellman                                                                                        = js.native
   def createDiffieHellman(prime: BufferLike, generator: String, generatorEncoding: String): DiffieHellman = js.native
-  def createDiffieHellman(prime: BufferLike, generator: Int | BufferLike): DiffieHellman                  = js.native
-  def createDiffieHellman(primeLength: Int, generator: Int | String | BufferLike): DiffieHellman          = js.native
+  def createDiffieHellman(prime: BufferLike, generator: Int): DiffieHellman                               = js.native
+  def createDiffieHellman(prime: BufferLike, generator: BufferLike): DiffieHellman                        = js.native
+  def createDiffieHellman(primeLength: Int, generator: Int): DiffieHellman                                = js.native
 
   def createDiffieHellmanGroup(name: String): DiffieHellman = js.native
 
@@ -127,18 +135,32 @@ trait Crypto extends js.Object {
     * @param algorithm the given algorithm (e.g. 'sha256', 'sha512')
     * @param key       The key is the HMAC key used to generate the cryptographic HMAC hash.
     */
-  def createHmac(algorithm: String, key: String | BufferLike, options: TransformOptions): Hmac = js.native
-  def createHmac(algorithm: String, key: String | BufferLike): Hmac                            = js.native
+  def createHmac(algorithm: String, key: String, options: TransformOptions): Hmac     = js.native
+  def createHmac(algorithm: String, key: BufferLike, options: TransformOptions): Hmac = js.native
+  def createHmac(algorithm: String, key: String): Hmac                                = js.native
+  def createHmac(algorithm: String, key: BufferLike): Hmac                            = js.native
   @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12)
   def createHmac(algorithm: String, key: KeyObject, options: TransformOptions): Hmac = js.native
   @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12)
   def createHmac(algorithm: String, key: KeyObject): Hmac = js.native
 
-  @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12)
-  def createPrivateKey(key: String | Buffer | CreatePrivateKeyOptions): KeyObject = js.native
+  @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12) def createPrivateKey(key: String): KeyObject =
+    js.native
+  @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12) def createPrivateKey(key: Buffer): KeyObject =
+    js.native
+  @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12) def createPrivateKey(
+      key: CreatePrivateKeyOptions
+  ): KeyObject = js.native
 
-  @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12)
-  def createPublicKey(key: String | Buffer | KeyObject | CreatePublicKeyOptions): KeyObject = js.native
+  @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12) def createPublicKey(key: String): KeyObject =
+    js.native
+  @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12) def createPublicKey(key: Buffer): KeyObject =
+    js.native
+  @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12) def createPublicKey(key: KeyObject): KeyObject =
+    js.native
+  @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12) def createPublicKey(
+      key: CreatePublicKeyOptions
+  ): KeyObject = js.native
 
   @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12)
   def createSecretKey(key: Buffer): KeyObject = js.native
@@ -184,8 +206,29 @@ trait Crypto extends js.Object {
 
   def getHashes(): js.Array[String] = js.native
 
-  def pbkdf2(password: String | BufferLike,
-             salt: String | BufferLike,
+  def pbkdf2(password: String,
+             salt: String,
+             iterations: Int,
+             keylen: Int,
+             digest: String,
+             callback: Callback1[Buffer]
+  ): Buffer = js.native
+  def pbkdf2(password: String,
+             salt: BufferLike,
+             iterations: Int,
+             keylen: Int,
+             digest: String,
+             callback: Callback1[Buffer]
+  ): Buffer = js.native
+  def pbkdf2(password: BufferLike,
+             salt: String,
+             iterations: Int,
+             keylen: Int,
+             digest: String,
+             callback: Callback1[Buffer]
+  ): Buffer = js.native
+  def pbkdf2(password: BufferLike,
+             salt: BufferLike,
              iterations: Int,
              keylen: Int,
              digest: String,
@@ -207,26 +250,29 @@ trait Crypto extends js.Object {
     *
     * (Doc source: https://nodejs.org/api/crypto.html#crypto_crypto_pbkdf2sync_password_salt_iterations_keylen_digest)
     */
-  def pbkdf2Sync(password: String | BufferLike,
-                 salt: String | BufferLike,
-                 iterations: Int,
-                 keylen: Int,
-                 digest: String
-  ): Buffer = js.native
+  def pbkdf2Sync(password: String, salt: String, iterations: Int, keylen: Int, digest: String): Buffer     = js.native
+  def pbkdf2Sync(password: String, salt: BufferLike, iterations: Int, keylen: Int, digest: String): Buffer = js.native
+  def pbkdf2Sync(password: BufferLike, salt: String, iterations: Int, keylen: Int, digest: String): Buffer = js.native
+  def pbkdf2Sync(password: BufferLike, salt: BufferLike, iterations: Int, keylen: Int, digest: String): Buffer =
+    js.native
 
-  def privateDecrypt(privateKey: String | Buffer, buffer: BufferLike): Buffer = js.native
+  def privateDecrypt(privateKey: String, buffer: BufferLike): Buffer = js.native
+  def privateDecrypt(privateKey: Buffer, buffer: BufferLike): Buffer = js.native
   @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12)
   def privateDecrypt(privateKey: PrivateDecryptKeyObject, buffer: BufferLike): Buffer = js.native
 
-  def privateEncrypt(privateKey: String | Buffer, buffer: BufferLike): Buffer = js.native
+  def privateEncrypt(privateKey: String, buffer: BufferLike): Buffer = js.native
+  def privateEncrypt(privateKey: Buffer, buffer: BufferLike): Buffer = js.native
   @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12)
   def privateEncrypt(privateKey: PrivateEncryptKeyObject, buffer: BufferLike): Buffer = js.native
 
-  def publicDecrypt(key: String | Buffer, buffer: BufferLike): Buffer = js.native
+  def publicDecrypt(key: String, buffer: BufferLike): Buffer = js.native
+  def publicDecrypt(key: Buffer, buffer: BufferLike): Buffer = js.native
   @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12)
   def publicDecrypt(key: PublicDecryptKeyObject, buffer: BufferLike): Buffer = js.native
 
-  def publicEncrypt(key: String | Buffer, buffer: BufferLike): Buffer = js.native
+  def publicEncrypt(key: String, buffer: BufferLike): Buffer = js.native
+  def publicEncrypt(key: Buffer, buffer: BufferLike): Buffer = js.native
   @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12)
   def publicEncrypt(key: PublicEncryptKeyObject, buffer: BufferLike): Buffer = js.native
 
@@ -277,21 +323,39 @@ trait Crypto extends js.Object {
     js.native
   def randomFill[T <: scala.scalajs.js.typedarray.TypedArray[_, T]](buffer: T, callback: Callback1[T]): T = js.native
 
-  def scrypt(password: String | BufferLike,
-             salt: String | BufferLike,
+  def scrypt(password: String, salt: String, keylen: Int, options: ScryptOptions, callback: Callback1[Buffer]): Unit =
+    js.native
+  def scrypt(password: String,
+             salt: BufferLike,
              keylen: Int,
              options: ScryptOptions,
              callback: Callback1[Buffer]
   ): Unit = js.native
-  def scrypt(password: String | BufferLike, salt: String | BufferLike, keylen: Int, callback: Callback1[Buffer]): Unit =
-    js.native
-
-  def scryptSync(password: String | BufferLike,
-                 salt: String | BufferLike,
-                 keylen: Int,
-                 options: ScryptOptions
-  ): Buffer                                                                                     = js.native
-  def scryptSync(password: String | BufferLike, salt: String | BufferLike, keylen: Int): Buffer = js.native
+  def scrypt(password: BufferLike,
+             salt: String,
+             keylen: Int,
+             options: ScryptOptions,
+             callback: Callback1[Buffer]
+  ): Unit = js.native
+  def scrypt(password: BufferLike,
+             salt: BufferLike,
+             keylen: Int,
+             options: ScryptOptions,
+             callback: Callback1[Buffer]
+  ): Unit                                                                                            = js.native
+  def scrypt(password: String, salt: String, keylen: Int, callback: Callback1[Buffer]): Unit         = js.native
+  def scrypt(password: String, salt: BufferLike, keylen: Int, callback: Callback1[Buffer]): Unit     = js.native
+  def scrypt(password: BufferLike, salt: String, keylen: Int, callback: Callback1[Buffer]): Unit     = js.native
+  def scrypt(password: BufferLike, salt: BufferLike, keylen: Int, callback: Callback1[Buffer]): Unit = js.native
+
+  def scryptSync(password: String, salt: String, keylen: Int, options: ScryptOptions): Buffer         = js.native
+  def scryptSync(password: String, salt: BufferLike, keylen: Int, options: ScryptOptions): Buffer     = js.native
+  def scryptSync(password: BufferLike, salt: String, keylen: Int, options: ScryptOptions): Buffer     = js.native
+  def scryptSync(password: BufferLike, salt: BufferLike, keylen: Int, options: ScryptOptions): Buffer = js.native
+  def scryptSync(password: String, salt: String, keylen: Int): Buffer                                 = js.native
+  def scryptSync(password: String, salt: BufferLike, keylen: Int): Buffer                             = js.native
+  def scryptSync(password: BufferLike, salt: String, keylen: Int): Buffer                             = js.native
+  def scryptSync(password: BufferLike, salt: BufferLike, keylen: Int): Buffer                         = js.native
 
   def setEngine(engine: String, fips: Int): Unit = js.native
   def setEngine(engine: String): Unit            = js.native
@@ -300,20 +364,46 @@ trait Crypto extends js.Object {
 
   @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12) def sign(algorithm: String,
                                                                               data: BufferLike,
-                                                                              key: String | Buffer | KeyObject
+                                                                              key: String
+  ): Buffer = js.native
+  @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12) def sign(algorithm: String,
+                                                                              data: BufferLike,
+                                                                              key: Buffer
+  ): Buffer = js.native
+  @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12) def sign(algorithm: String,
+                                                                              data: BufferLike,
+                                                                              key: KeyObject
   ): Buffer = js.native
+  @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12) def sign(data: BufferLike, key: String): Buffer =
+    js.native
+  @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12) def sign(data: BufferLike, key: Buffer): Buffer =
+    js.native
   @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12) def sign(data: BufferLike,
-                                                                              key: String | Buffer | KeyObject
+                                                                              key: KeyObject
   ): Buffer = js.native
 
   def timingSafeEqual(a: BufferLike, b: BufferLike): Boolean = js.native
 
   @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12) def verify(algorithm: String,
                                                                                 data: BufferLike,
-                                                                                key: String | Buffer | KeyObject
+                                                                                key: String
+  ): Boolean = js.native
+  @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12) def verify(algorithm: String,
+                                                                                data: BufferLike,
+                                                                                key: Buffer
+  ): Boolean = js.native
+  @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12) def verify(algorithm: String,
+                                                                                data: BufferLike,
+                                                                                key: KeyObject
+  ): Boolean = js.native
+  @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12) def verify(data: BufferLike,
+                                                                                key: String
+  ): Boolean = js.native
+  @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12) def verify(data: BufferLike,
+                                                                                key: Buffer
   ): Boolean = js.native
   @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12) def verify(data: BufferLike,
-                                                                                key: String | Buffer | KeyObject
+                                                                                key: KeyObject
   ): Boolean = js.native
 }
 
diff --git a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/crypto/Sign.scala b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/crypto/Sign.scala
index 7312fc2b7..944d9d7f3 100644
--- a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/crypto/Sign.scala
+++ b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/crypto/Sign.scala
@@ -19,8 +19,10 @@ import scala.scalajs.js.|
   */
 @js.native
 sealed trait Sign extends Writable {
-  def sign(privateKey: String | Buffer): Buffer                         = js.native
-  def sign(privateKey: String | Buffer, outputEncoding: String): String = js.native
+  def sign(privateKey: String): Buffer                         = js.native
+  def sign(privateKey: Buffer): Buffer                         = js.native
+  def sign(privateKey: String, outputEncoding: String): String = js.native
+  def sign(privateKey: Buffer, outputEncoding: String): String = js.native
   @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12)
   def sign(privateKey: KeyObject): Buffer = js.native
   @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12)
diff --git a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/crypto/Verify.scala b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/crypto/Verify.scala
index 66c3fbb8f..741581290 100644
--- a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/crypto/Verify.scala
+++ b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/crypto/Verify.scala
@@ -44,8 +44,10 @@ trait Verify extends Writable {
     *                         signature is expected to be a Buffer.
     * @return true or false depending on the validity of the signature for the data and public key.
     */
-  def verify(obj: String | Buffer, signature: String, signatureEncoding: String): Boolean = js.native
-  def verify(obj: String | Buffer, signature: BufferLike): Boolean                        = js.native
+  def verify(obj: String, signature: String, signatureEncoding: String): Boolean = js.native
+  def verify(obj: Buffer, signature: String, signatureEncoding: String): Boolean = js.native
+  def verify(obj: String, signature: BufferLike): Boolean                        = js.native
+  def verify(obj: Buffer, signature: BufferLike): Boolean                        = js.native
   @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12)
   def verify(obj: KeyObject, signature: String, signatureEncoding: String): Boolean = js.native
   @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12)
diff --git a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/dns/DNS.scala b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/dns/DNS.scala
index 9a4a98cdd..ae2f35307 100644
--- a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/dns/DNS.scala
+++ b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/dns/DNS.scala
@@ -35,7 +35,9 @@ trait DNS extends IResolver {
     * All properties are optional.
     * @example dns.lookup(hostname[, options], callback)
     */
-  def lookup(hostname: String, options: DnsOptions | Int, callback: DnsCallback2[String, Int]): Unit = js.native
+  def lookup(hostname: String, options: DnsOptions, callback: DnsCallback2[String, Int]): Unit = js.native
+  def lookup(hostname: String, options: Int, callback: DnsCallback2[String, Int]): Unit        = js.native
+  def lookup(hostname: String, callback: DnsCallback2[String, Int]): Unit                      = js.native
 
   /**
     * Resolves a hostname (e.g. 'nodejs.org') into the first found A (IPv4) or AAAA (IPv6) record. options can be an
diff --git a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/dns/package.scala b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/dns/package.scala
index 3de8ff27f..79b920d73 100644
--- a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/dns/package.scala
+++ b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/dns/package.scala
@@ -70,9 +70,17 @@ package object dns {
       * integer, then it must be 4 or 6.
       */
     @inline
-    def lookupFuture(hostname: String, options: DnsOptions | Int = null): Future[(String, Int)] = {
+    def lookupFuture(hostname: String, family: Int): Future[(String, Int)] = {
+      promiseWithError2[DnsError, String, Int](dns.lookup(hostname, family, _))
+    }
+    @inline
+    def lookupFuture(hostname: String, options: DnsOptions): Future[(String, Int)] = {
       promiseWithError2[DnsError, String, Int](dns.lookup(hostname, options, _))
     }
+    @inline
+    def lookupFuture(hostname: String): Future[(String, Int)] = {
+      promiseWithError2[DnsError, String, Int](dns.lookup(hostname, _))
+    }
 
     /**
       * Resolves the given address and port into a hostname and service using the operating system's underlying
diff --git a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/fs/Fs.scala b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/fs/Fs.scala
index d931fc983..248ca9dbb 100644
--- a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/fs/Fs.scala
+++ b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/fs/Fs.scala
@@ -87,11 +87,12 @@ trait Fs extends js.Object with FSConstants {
     * @param callback the callback function
     * @example fs.appendFile(file, data[, options], callback)
     */
-  def appendFile(file: Path | FileDescriptor,
-                 data: Buffer | String,
-                 options: FileAppendOptions,
-                 callback: FsCallback0
-  ): Unit = js.native
+  def appendFile(file: Path, data: Buffer, options: FileAppendOptions, callback: FsCallback0): Unit = js.native
+  def appendFile(file: Path, data: String, options: FileAppendOptions, callback: FsCallback0): Unit = js.native
+  def appendFile(file: FileDescriptor, data: Buffer, options: FileAppendOptions, callback: FsCallback0): Unit =
+    js.native
+  def appendFile(file: FileDescriptor, data: String, options: FileAppendOptions, callback: FsCallback0): Unit =
+    js.native
 
   /**
     * Asynchronously append data to a file, creating the file if it does not yet exist. data can be a string or a buffer.
@@ -100,7 +101,10 @@ trait Fs extends js.Object with FSConstants {
     * @param callback the callback function
     * @example fs.appendFile(file, data[, options], callback)
     */
-  def appendFile(path: Path | FileDescriptor, data: Buffer | String, callback: FsCallback0): Unit = js.native
+  def appendFile(path: Path, data: Buffer, callback: FsCallback0): Unit           = js.native
+  def appendFile(path: Path, data: String, callback: FsCallback0): Unit           = js.native
+  def appendFile(path: FileDescriptor, data: Buffer, callback: FsCallback0): Unit = js.native
+  def appendFile(path: FileDescriptor, data: String, callback: FsCallback0): Unit = js.native
 
   /**
     * The synchronous version of fs.appendFile().
@@ -109,8 +113,14 @@ trait Fs extends js.Object with FSConstants {
     * @param options the [[FileAppendOptions optional append settings]]
     * @return undefined.
     */
-  def appendFileSync(path: Path | FileDescriptor, data: Buffer | String, options: FileAppendOptions): Unit = js.native
-  def appendFileSync(path: Path | FileDescriptor, data: Buffer | String): Unit                             = js.native
+  def appendFileSync(path: Path, data: Buffer, options: FileAppendOptions): Unit           = js.native
+  def appendFileSync(path: Path, data: String, options: FileAppendOptions): Unit           = js.native
+  def appendFileSync(path: Path, data: Buffer): Unit                                       = js.native
+  def appendFileSync(path: Path, data: String): Unit                                       = js.native
+  def appendFileSync(path: FileDescriptor, data: Buffer, options: FileAppendOptions): Unit = js.native
+  def appendFileSync(path: FileDescriptor, data: String, options: FileAppendOptions): Unit = js.native
+  def appendFileSync(path: FileDescriptor, data: Buffer): Unit                             = js.native
+  def appendFileSync(path: FileDescriptor, data: String): Unit                             = js.native
 
   /**
     * Asynchronous chmod(2). No arguments other than a possible exception are given to the completion callback.
@@ -435,7 +445,8 @@ trait Fs extends js.Object with FSConstants {
     * After v13.11.0, in recursive mode, the `callback`` now receives the first created path as an 2nd argument.
     * @example fs.mkdir(path[, mode], callback)
     */
-  def mkdir(path: Path, mode: MkdirOptions, callback: FsCallback0 | FsRecursiveCallback0): Unit = js.native
+  def mkdir(path: Path, mode: MkdirOptions, callback: FsCallback0): Unit          = js.native
+  def mkdir(path: Path, mode: MkdirOptions, callback: FsRecursiveCallback0): Unit = js.native
 
   /**
     * Asynchronous mkdir(2). No arguments other than a possible exception are given to the completion callback.
@@ -468,8 +479,8 @@ trait Fs extends js.Object with FSConstants {
     * @param callback the callback
     * @example fs.mkdtemp(prefix[, options], callback)
     */
-  def mkdtemp(prefix: String, options: String | FileEncodingOptions, callback: FsCallback1[String]): Unit =
-    js.native
+  def mkdtemp(prefix: String, options: String, callback: FsCallback1[String]): Unit              = js.native
+  def mkdtemp(prefix: String, options: FileEncodingOptions, callback: FsCallback1[String]): Unit = js.native
 
   /**
     * Creates a unique temporary directory.
@@ -490,8 +501,9 @@ trait Fs extends js.Object with FSConstants {
     * @param prefix  the prefix
     * @param options the optional encoding setting
     */
-  def mkdtempSync(prefix: String, options: String | FileEncodingOptions): String = js.native
-  def mkdtempSync(prefix: String): String                                        = js.native
+  def mkdtempSync(prefix: String, options: String): String              = js.native
+  def mkdtempSync(prefix: String, options: FileEncodingOptions): String = js.native
+  def mkdtempSync(prefix: String): String                               = js.native
 
   /**
     * Asynchronous file open. See open(2).
@@ -645,8 +657,9 @@ trait Fs extends js.Object with FSConstants {
     *                 of the names of the files in the directory excluding '.' and '..'.
     * @example fs.readdir(path[, options], callback)
     */
-  def readdir(path: Path, options: String | FileEncodingOptions, callback: FsCallback1[ReaddirArrays]): Unit = js.native
-  def readdir(path: Path, options: ReaddirOptions, callback: FsCallback1[ReaddirArrays2]): Unit              = js.native
+  def readdir(path: Path, options: String, callback: FsCallback1[ReaddirArrays]): Unit              = js.native
+  def readdir(path: Path, options: FileEncodingOptions, callback: FsCallback1[ReaddirArrays]): Unit = js.native
+  def readdir(path: Path, options: ReaddirOptions, callback: FsCallback1[ReaddirArrays2]): Unit     = js.native
 
   /**
     * Asynchronous readdir(3). Reads the contents of a directory.
@@ -678,7 +691,8 @@ trait Fs extends js.Object with FSConstants {
     *                 If no encoding is specified, then the raw buffer is returned.
     * @example fs.readFile(file[, options], callback)
     */
-  def readFile(file: Path | FileDescriptor, options: ReadFileOptions, callback: FsCallback1[Output]): Unit = js.native
+  def readFile(file: Path, options: ReadFileOptions, callback: FsCallback1[Output]): Unit           = js.native
+  def readFile(file: FileDescriptor, options: ReadFileOptions, callback: FsCallback1[Output]): Unit = js.native
 
   /**
     * Asynchronously reads the entire contents of a file.
@@ -688,8 +702,8 @@ trait Fs extends js.Object with FSConstants {
     *                 If no encoding is specified, then the raw buffer is returned.
     * @example fs.readFile(file[, options], callback)
     */
-  def readFile(file: Path | FileDescriptor, encoding: String, callback: FsCallback1[String]): Unit =
-    js.native
+  def readFile(file: Path, encoding: String, callback: FsCallback1[String]): Unit           = js.native
+  def readFile(file: FileDescriptor, encoding: String, callback: FsCallback1[String]): Unit = js.native
 
   /**
     * Asynchronously reads the entire contents of a file.
@@ -698,7 +712,8 @@ trait Fs extends js.Object with FSConstants {
     *                 If no encoding is specified, then the raw buffer is returned.
     * @example fs.readFile(file[, options], callback)
     */
-  def readFile(file: Path | FileDescriptor, callback: FsCallback1[Buffer]): Unit = js.native
+  def readFile(file: Path, callback: FsCallback1[Buffer]): Unit           = js.native
+  def readFile(file: FileDescriptor, callback: FsCallback1[Buffer]): Unit = js.native
 
   /**
     * Synchronous version of fs.readFile. Returns the contents of the file.
@@ -708,7 +723,8 @@ trait Fs extends js.Object with FSConstants {
     *         Otherwise it returns a buffer.
     * @example fs.readFileSync(file[, options])
     */
-  def readFileSync(file: Path | FileDescriptor, encoding: String): String = js.native
+  def readFileSync(file: Path, encoding: String): String           = js.native
+  def readFileSync(file: FileDescriptor, encoding: String): String = js.native
 
   /**
     * Synchronous version of fs.readFile. Returns the contents of the file.
@@ -718,7 +734,8 @@ trait Fs extends js.Object with FSConstants {
     *         Otherwise it returns a buffer.
     * @example fs.readFileSync(file[, options])
     */
-  def readFileSync(file: Path | FileDescriptor, options: ReadFileOptions): Output = js.native
+  def readFileSync(file: Path, options: ReadFileOptions): Output           = js.native
+  def readFileSync(file: FileDescriptor, options: ReadFileOptions): Output = js.native
 
   /**
     * Synchronous version of fs.readFile.
@@ -727,7 +744,8 @@ trait Fs extends js.Object with FSConstants {
     *         Otherwise it returns a buffer.
     * @example fs.readFileSync(file[, options])
     */
-  def readFileSync(file: Path | FileDescriptor): Buffer = js.native
+  def readFileSync(file: Path): Buffer           = js.native
+  def readFileSync(file: FileDescriptor): Buffer = js.native
 
   /**
     * Asynchronous readlink(2).
@@ -739,9 +757,9 @@ trait Fs extends js.Object with FSConstants {
     * @param callback the callback gets two arguments (err, linkString).
     * @example fs.readlink(path[, options], callback)
     */
-  def readlink(path: Path, options: String | FileEncodingOptions, callback: FsCallback1[Output]): Unit =
-    js.native
-  def readlink(path: Path, callback: FsCallback1[String]): Unit = js.native
+  def readlink(path: Path, options: String, callback: FsCallback1[Output]): Unit              = js.native
+  def readlink(path: Path, options: FileEncodingOptions, callback: FsCallback1[Output]): Unit = js.native
+  def readlink(path: Path, callback: FsCallback1[String]): Unit                               = js.native
 
   /**
     * Synchronous readlink(2).
@@ -752,8 +770,9 @@ trait Fs extends js.Object with FSConstants {
     *                to 'buffer', the link path returned will be passed as a Buffer object.
     * @return the symbolic link's string value.
     */
-  def readlinkSync(path: Path, options: String | FileEncodingOptions): Output = js.native
-  def readlinkSync(path: Path): String                                        = js.native
+  def readlinkSync(path: Path, options: String): Output              = js.native
+  def readlinkSync(path: Path, options: FileEncodingOptions): Output = js.native
+  def readlinkSync(path: Path): String                               = js.native
 
   /**
     * Asynchronous realpath(2).
@@ -766,8 +785,8 @@ trait Fs extends js.Object with FSConstants {
     *                 the path returned will be passed as a Buffer object.
     * @example fs.realpath(path[, options], callback)
     */
-  def realpath(path: Path, options: String | FileEncodingOptions, callback: FsCallback1[Output]): Unit =
-    js.native
+  def realpath(path: Path, options: String, callback: FsCallback1[Output]): Unit              = js.native
+  def realpath(path: Path, options: FileEncodingOptions, callback: FsCallback1[Output]): Unit = js.native
 
   /**
     * Asynchronous realpath(2). The callback gets two arguments (err, resolvedPath).
@@ -1099,13 +1118,18 @@ trait Fs extends js.Object with FSConstants {
     * @return undefined.
     * @example fs.writeFileSync(file, data[, options])
     */
-  def writeFileSync(file: Path | FileDescriptor, data: js.typedarray.Uint8Array, options: FileWriteOptions): Unit =
-    js.native
-  def writeFileSync(file: Path | FileDescriptor, data: js.typedarray.Uint8Array): Unit              = js.native
-  def writeFileSync(file: Path | FileDescriptor, data: String, options: FileWriteOptions): Unit     = js.native
-  def writeFileSync(file: Path | FileDescriptor, data: String): Unit                                = js.native
-  def writeFileSync(file: Path | FileDescriptor, data: BufferLike, options: FileWriteOptions): Unit = js.native
-  def writeFileSync(file: Path | FileDescriptor, data: BufferLike): Unit                            = js.native
+  def writeFileSync(file: Path, data: js.typedarray.Uint8Array, options: FileWriteOptions): Unit           = js.native
+  def writeFileSync(file: Path, data: js.typedarray.Uint8Array): Unit                                      = js.native
+  def writeFileSync(file: Path, data: String, options: FileWriteOptions): Unit                             = js.native
+  def writeFileSync(file: Path, data: String): Unit                                                        = js.native
+  def writeFileSync(file: Path, data: BufferLike, options: FileWriteOptions): Unit                         = js.native
+  def writeFileSync(file: Path, data: BufferLike): Unit                                                    = js.native
+  def writeFileSync(file: FileDescriptor, data: js.typedarray.Uint8Array, options: FileWriteOptions): Unit = js.native
+  def writeFileSync(file: FileDescriptor, data: js.typedarray.Uint8Array): Unit                            = js.native
+  def writeFileSync(file: FileDescriptor, data: String, options: FileWriteOptions): Unit                   = js.native
+  def writeFileSync(file: FileDescriptor, data: String): Unit                                              = js.native
+  def writeFileSync(file: FileDescriptor, data: BufferLike, options: FileWriteOptions): Unit               = js.native
+  def writeFileSync(file: FileDescriptor, data: BufferLike): Unit                                          = js.native
 
   /**
     * Write buffer to the file specified by fd.
@@ -1162,10 +1186,14 @@ object Fs extends Fs {
   trait FsPromises extends js.Object {
     def access(path: Path, mode: FileMode): js.Promise[Unit] = js.native
 
-    def appendFile(file: Path | FileDescriptor, data: String | Buffer, options: FileAppendOptions): js.Promise[Unit] =
-      js.native
-    def appendFile(file: Path | FileDescriptor, data: String | Buffer, encoding: String): js.Promise[Unit] = js.native
-    def appendFile(file: Path | FileDescriptor, data: String | Buffer): js.Promise[Unit]                   = js.native
+    def appendFile(file: Path, data: String, options: FileAppendOptions): js.Promise[Unit]           = js.native
+    def appendFile(file: FileDescriptor, data: Buffer, options: FileAppendOptions): js.Promise[Unit] = js.native
+    def appendFile(file: Path, data: String, encoding: String): js.Promise[Unit]                     = js.native
+    def appendFile(file: FileDescriptor, data: Buffer, encoding: String): js.Promise[Unit]           = js.native
+    def appendFile(file: Path, data: String): js.Promise[Unit]                                       = js.native
+    def appendFile(file: Path, data: Buffer): js.Promise[Unit]                                       = js.native
+    def appendFile(file: FileDescriptor, data: String): js.Promise[Unit]                             = js.native
+    def appendFile(file: FileDescriptor, data: Buffer): js.Promise[Unit]                             = js.native
 
     def chmod(path: Path, mode: FileMode): js.Promise[Unit]                       = js.native
     def chown(path: Path, uid: UID, gid: GID): js.Promise[Unit]                   = js.native
@@ -1194,33 +1222,40 @@ object Fs extends Fs {
     def readdir(path: Path, options: FileEncodingOptions): js.Promise[js.Array[String]]               = js.native
     def readdir(path: Path): js.Promise[js.Array[String]]                                             = js.native
     def readlink(path: Path): js.Promise[String]                                                      = js.native
-    def readlink(path: Path, options: String | FileEncodingOptions): js.Promise[Output]               = js.native
+    def readlink(path: Path, options: String): js.Promise[Output]                                     = js.native
+    def readlink(path: Path, options: FileEncodingOptions): js.Promise[Output]                        = js.native
     def rename(oldPath: Path, newPath: Path): js.Promise[Unit]                                        = js.native
     def rmdir(path: Path): js.Promise[Unit]                                                           = js.native
     @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12)
-    def rmdir(path: Path, options: RmdirOptions): js.Promise[Unit]          = js.native
-    def stat(path: Path, options: StatOptions): js.Promise[StatsVariant]    = js.native
-    def stat(path: Path): js.Promise[StatsVariant]                          = js.native
-    def symlink(target: Path, path: Path, `type`: String): js.Promise[Unit] = js.native
-    def symlink(target: Path, path: Path): js.Promise[Unit]                 = js.native
-    def truncate(path: Path, length: Int): js.Promise[Unit]                 = js.native
-    def truncate(path: Path): js.Promise[Unit]                              = js.native
-    def unlink(path: Path): js.Promise[Unit]                                = js.native
-    def utimes(path: Path, atime: Time, mtime: Time): js.Promise[Unit]      = js.native
-    def writeFile(file: Path | FileHandle, data: String | BufferLike, options: FileWriteOptions): js.Promise[Unit] =
-      js.native
+    def rmdir(path: Path, options: RmdirOptions): js.Promise[Unit]                                 = js.native
+    def stat(path: Path, options: StatOptions): js.Promise[StatsVariant]                           = js.native
+    def stat(path: Path): js.Promise[StatsVariant]                                                 = js.native
+    def symlink(target: Path, path: Path, `type`: String): js.Promise[Unit]                        = js.native
+    def symlink(target: Path, path: Path): js.Promise[Unit]                                        = js.native
+    def truncate(path: Path, length: Int): js.Promise[Unit]                                        = js.native
+    def truncate(path: Path): js.Promise[Unit]                                                     = js.native
+    def unlink(path: Path): js.Promise[Unit]                                                       = js.native
+    def utimes(path: Path, atime: Time, mtime: Time): js.Promise[Unit]                             = js.native
+    def writeFile(file: Path, data: String, options: FileWriteOptions): js.Promise[Unit]           = js.native
+    def writeFile(file: Path, data: BufferLike, options: FileWriteOptions): js.Promise[Unit]       = js.native
+    def writeFile(file: FileHandle, data: String, options: FileWriteOptions): js.Promise[Unit]     = js.native
+    def writeFile(file: FileHandle, data: BufferLike, options: FileWriteOptions): js.Promise[Unit] = js.native
   }
 
   @js.native
   trait FileHandle extends js.Object {
     val fd: FileDescriptor = js.native
 
-    def appendFile(data: String | Buffer, options: FileAppendOptions): js.Promise[Unit] = js.native
-    def appendFile(data: String | Buffer): js.Promise[Unit]                             = js.native
-    def chmod(mode: FileMode): js.Promise[Unit]                                         = js.native
-    def chown(uid: UID, gid: GID): js.Promise[Unit]                                     = js.native
-    def close(): js.Promise[Unit]                                                       = js.native
-    def datasync(): js.Promise[Unit]                                                    = js.native
+    def appendFile(data: String, options: FileAppendOptions): js.Promise[Unit] = js.native
+    def appendFile(data: String): js.Promise[Unit]                             = js.native
+    def appendFile(data: Buffer, options: FileAppendOptions): js.Promise[Unit] = js.native
+    def appendFile(data: Buffer): js.Promise[Unit]                             = js.native
+
+    def chmod(mode: FileMode): js.Promise[Unit]     = js.native
+    def chown(uid: UID, gid: GID): js.Promise[Unit] = js.native
+    def close(): js.Promise[Unit]                   = js.native
+    def datasync(): js.Promise[Unit]                = js.native
+
     def read[T <: js.typedarray.TypedArray[_, _]](buffer: T,
                                                   offset: Int | Null,
                                                   length: Int | Null,
@@ -1238,6 +1273,7 @@ object Fs extends Fs {
     def truncate(): js.Promise[Unit]                           = js.native
     def truncate(length: Int): js.Promise[Unit]                = js.native
     def utimes(atime: Time, mtime: Time): js.Promise[Unit]     = js.native
+
     def write[T <: js.typedarray.TypedArray[_, _]](buffer: T,
                                                    offset: Int | Null,
                                                    length: Int | Null,
@@ -1249,10 +1285,16 @@ object Fs extends Fs {
               position: Int | Null
     ): js.Promise[BufferIOResult[js.typedarray.DataView]]                                                 = js.native
     def write(string: String, position: Int | Null, encoding: String): js.Promise[BufferIOResult[String]] = js.native
-    def writeFile(data: String | BufferLike, options: FileWriteOptions): js.Promise[Unit]                 = js.native
-    def writeFile(data: String | BufferLike): js.Promise[Unit]                                            = js.native
+
+    def writeFile(data: String, options: FileWriteOptions): js.Promise[Unit]     = js.native
+    def writeFile(data: String): js.Promise[Unit]                                = js.native
+    def writeFile(data: BufferLike, options: FileWriteOptions): js.Promise[Unit] = js.native
+    def writeFile(data: BufferLike): js.Promise[Unit]                            = js.native
+
+    @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12)
+    def writev(buffers: js.Array[js.typedarray.ArrayBufferView], position: Int): js.Promise[Unit] = js.native
     @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12)
-    def writev(buffers: js.Array[js.typedarray.ArrayBufferView], position: Int | Null): js.Promise[Unit] = js.native
+    def writev(buffers: js.Array[js.typedarray.ArrayBufferView]): js.Promise[Unit] = js.native
   }
 
   val promises: FsPromises = js.native
diff --git a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/fs/package.scala b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/fs/package.scala
index 94712ef99..cad8c40f2 100644
--- a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/fs/package.scala
+++ b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/fs/package.scala
@@ -37,25 +37,50 @@ package object fs {
     */
   implicit final class FsExtensions(private val instance: Fs) extends AnyVal {
     @inline
-    def accessFuture(path: Buffer | String): Future[Unit] = {
+    def accessFuture(path: Path): Future[Unit] = {
       promiseWithError0[FileIOError](instance.access(path, _))
     }
 
     @inline
-    def accessFuture(path: Buffer | String, mode: FileMode): Future[Unit] = {
+    def accessFuture(path: Path, mode: FileMode): Future[Unit] = {
       promiseWithError0[FileIOError](instance.access(path, mode, _))
     }
 
     @inline
-    def appendFileFuture(file: Buffer | FileDescriptor | String,
-                         data: Buffer | String,
-                         options: FileAppendOptions = null
-    ): Future[Unit] = {
+    def appendFileFuture(file: Path, data: Buffer, options: FileAppendOptions): Future[Unit] = {
       promiseWithError0[FileIOError](instance.appendFile(file, data, options, _))
     }
+    @inline
+    def appendFileFuture(file: Path, data: String, options: FileAppendOptions): Future[Unit] = {
+      promiseWithError0[FileIOError](instance.appendFile(file, data, options, _))
+    }
+    @inline
+    def appendFileFuture(file: FileDescriptor, data: Buffer, options: FileAppendOptions): Future[Unit] = {
+      promiseWithError0[FileIOError](instance.appendFile(file, data, options, _))
+    }
+    @inline
+    def appendFileFuture(file: FileDescriptor, data: String, options: FileAppendOptions): Future[Unit] = {
+      promiseWithError0[FileIOError](instance.appendFile(file, data, options, _))
+    }
+    @inline
+    def appendFileFuture(file: Path, data: Buffer): Future[Unit] = {
+      promiseWithError0[FileIOError](instance.appendFile(file, data, _))
+    }
+    @inline
+    def appendFileFuture(file: Path, data: String): Future[Unit] = {
+      promiseWithError0[FileIOError](instance.appendFile(file, data, _))
+    }
+    @inline
+    def appendFileFuture(file: FileDescriptor, data: Buffer): Future[Unit] = {
+      promiseWithError0[FileIOError](instance.appendFile(file, data, _))
+    }
+    @inline
+    def appendFileFuture(file: FileDescriptor, data: String): Future[Unit] = {
+      promiseWithError0[FileIOError](instance.appendFile(file, data, _))
+    }
 
     @inline
-    def chmodFuture(path: Buffer | String, mode: FileMode): Future[Unit] = {
+    def chmodFuture(path: Path, mode: FileMode): Future[Unit] = {
       promiseWithError0[FileIOError](instance.chmod(path, mode, _))
     }
 
@@ -247,7 +272,18 @@ package object fs {
     }
 
     @inline
-    def readdirDirentFuture(path: Buffer | String): Future[js.Array[Dirent]] = {
+    def readdirDirentFuture(path: Buffer): Future[js.Array[Dirent]] = {
+      val callback: FsCallback1[js.Array[Dirent]] => Unit = { callback =>
+        instance.readdir(
+          path,
+          ReaddirOptions(withFileTypes = true),
+          callback.asInstanceOf[FsCallback1[ReaddirArrays2]]
+        )
+      }
+      promiseWithError1[FileIOError, js.Array[Dirent]](callback)
+    }
+    @inline
+    def readdirDirentFuture(path: String): Future[js.Array[Dirent]] = {
       val callback: FsCallback1[js.Array[Dirent]] => Unit = { callback =>
         instance.readdir(
           path,
@@ -259,22 +295,38 @@ package object fs {
     }
 
     @inline
-    def readFileFuture(file: Path | FileDescriptor, options: ReadFileOptions): Future[Output] = {
+    def readFileFuture(file: Path, options: ReadFileOptions): Future[Output] = {
+      promiseWithError1[FileIOError, Output](instance.readFile(file, options, _))
+    }
+    @inline
+    def readFileFuture(file: FileDescriptor, options: ReadFileOptions): Future[Output] = {
       promiseWithError1[FileIOError, Output](instance.readFile(file, options, _))
     }
 
     @inline
-    def readFileFuture(file: Path | FileDescriptor, encoding: String): Future[String] = {
+    def readFileFuture(file: Path, encoding: String): Future[String] = {
+      promiseWithError1[FileIOError, String](instance.readFile(file, encoding, _))
+    }
+    @inline
+    def readFileFuture(file: FileDescriptor, encoding: String): Future[String] = {
       promiseWithError1[FileIOError, String](instance.readFile(file, encoding, _))
     }
 
     @inline
-    def readFileFuture(file: Path | FileDescriptor): Future[Buffer] = {
+    def readFileFuture(file: Path): Future[Buffer] = {
+      promiseWithError1[FileIOError, Buffer](instance.readFile(file, _))
+    }
+    @inline
+    def readFileFuture(file: FileDescriptor): Future[Buffer] = {
       promiseWithError1[FileIOError, Buffer](instance.readFile(file, _))
     }
 
     @inline
-    def readlinkFuture(file: Path, options: String | FileEncodingOptions): Future[Output] = {
+    def readlinkFuture(file: Path, options: String): Future[Output] = {
+      promiseWithError1[FileIOError, Output](instance.readlink(file, options, _))
+    }
+    @inline
+    def readlinkFuture(file: Path, options: FileEncodingOptions): Future[Output] = {
       promiseWithError1[FileIOError, Output](instance.readlink(file, options, _))
     }
 
@@ -289,7 +341,11 @@ package object fs {
     }
 
     @inline
-    def realpathFuture(file: Path, options: String | FileEncodingOptions): Future[Output] = {
+    def realpathFuture(file: Path, options: String): Future[Output] = {
+      promiseWithError1[FileIOError, Output](instance.realpath(file, options, _))
+    }
+    @inline
+    def realpathFuture(file: Path, options: FileEncodingOptions): Future[Output] = {
       promiseWithError1[FileIOError, Output](instance.realpath(file, options, _))
     }
 
diff --git a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/http/Http.scala b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/http/Http.scala
index 67d6cdc2e..dc334e1f2 100644
--- a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/http/Http.scala
+++ b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/http/Http.scala
@@ -47,23 +47,30 @@ trait Http extends js.Object {
   def createServer(requestListener: js.Function2[ClientRequest, ServerResponse, Any]): Server = js.native
   def createServer(): Server                                                                  = js.native
 
-  def get(url: String | URL, options: RequestOptions, callback: js.Function1[ServerResponse, Any]): ClientRequest =
-    js.native
-  def get(url: String | URL, options: RequestOptions): ClientRequest                     = js.native
-  def get(url: String | URL, callback: js.Function1[ServerResponse, Any]): ClientRequest = js.native
-  def get(url: String | URL): ClientRequest                                              = js.native
-  def get(options: RequestOptions): ClientRequest                                        = js.native
-  def get(options: RequestOptions, callback: js.Function): ClientRequest                 = js.native
+  def get(url: String, options: RequestOptions, callback: js.Function1[ServerResponse, Any]): ClientRequest = js.native
+  def get(url: URL, options: RequestOptions, callback: js.Function1[ServerResponse, Any]): ClientRequest    = js.native
+  def get(url: String, options: RequestOptions): ClientRequest                                              = js.native
+  def get(url: String, callback: js.Function1[ServerResponse, Any]): ClientRequest                          = js.native
+  def get(url: String): ClientRequest                                                                       = js.native
+  def get(url: URL, options: RequestOptions): ClientRequest                                                 = js.native
+  def get(url: URL, callback: js.Function1[ServerResponse, Any]): ClientRequest                             = js.native
+  def get(url: URL): ClientRequest                                                                          = js.native
+  def get(options: RequestOptions): ClientRequest                                                           = js.native
+  def get(options: RequestOptions, callback: js.Function): ClientRequest                                    = js.native
 
   @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12)
   def maxHeaderSize: Int = js.native
 
-  def request(url: String | URL, options: RequestOptions): Unit                                              = js.native
-  def request(url: String | URL, options: RequestOptions, callback: js.Function1[ServerResponse, Any]): Unit = js.native
-  def request(url: String | URL, callback: js.Function1[ServerResponse, Any]): Unit                          = js.native
-  def request(url: String | URL): Unit                                                                       = js.native
-  def request(options: RequestOptions): Unit                                                                 = js.native
-  def request(options: RequestOptions, callback: js.Function1[ServerResponse, Any]): Unit                    = js.native
+  def request(url: String, options: RequestOptions): Unit                                              = js.native
+  def request(url: String, options: RequestOptions, callback: js.Function1[ServerResponse, Any]): Unit = js.native
+  def request(url: String, callback: js.Function1[ServerResponse, Any]): Unit                          = js.native
+  def request(url: String): Unit                                                                       = js.native
+  def request(url: URL, options: RequestOptions): Unit                                                 = js.native
+  def request(url: URL, options: RequestOptions, callback: js.Function1[ServerResponse, Any]): Unit    = js.native
+  def request(url: URL, callback: js.Function1[ServerResponse, Any]): Unit                             = js.native
+  def request(url: URL): Unit                                                                          = js.native
+  def request(options: RequestOptions): Unit                                                           = js.native
+  def request(options: RequestOptions, callback: js.Function1[ServerResponse, Any]): Unit              = js.native
 
   @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs14)
   def validateHeaderName(name: String): Unit = js.native
diff --git a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/http/ServerResponse.scala b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/http/ServerResponse.scala
index e44758dcd..53a6af264 100644
--- a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/http/ServerResponse.scala
+++ b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/http/ServerResponse.scala
@@ -127,10 +127,12 @@ trait ServerResponse extends stream.Writable {
   def writeContinue(): Unit = js.native
 
   // Todo: Return this.type when Node.js v10 dropped
-  def writeHead(statusCode: Int, statusMessage: String, headers: js.Object | js.Dictionary[_]): Unit = js.native
-  def writeHead(statusCode: Int, statusMessage: String): Unit                                        = js.native
-  def writeHead(statusCode: Int, headers: js.Object | js.Dictionary[_]): Unit                        = js.native
-  def writeHead(statusCode: Int): Unit                                                               = js.native
+  def writeHead(statusCode: Int, statusMessage: String, headers: js.Object): Unit        = js.native
+  def writeHead(statusCode: Int, statusMessage: String, headers: js.Dictionary[_]): Unit = js.native
+  def writeHead(statusCode: Int, statusMessage: String): Unit                            = js.native
+  def writeHead(statusCode: Int, headers: js.Object): Unit                               = js.native
+  def writeHead(statusCode: Int, headers: js.Dictionary[_]): Unit                        = js.native
+  def writeHead(statusCode: Int): Unit                                                   = js.native
 
   def writeProcessing(): Unit = js.native
 }
diff --git a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/http2/Http2.scala b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/http2/Http2.scala
index 98e778f8b..bb9306a00 100644
--- a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/http2/Http2.scala
+++ b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/http2/Http2.scala
@@ -17,8 +17,8 @@ trait Http2 extends js.Object {
     js.native
   def createSecureServer(options: Http2SecureServerOptions): Http2SecureServer = js.native
 
-  def connect(authority: String | URL, options: Http2ConnectOptions, listener: js.Function): ClientHttp2Session =
-    js.native
+  def connect(authority: String, options: Http2ConnectOptions, listener: js.Function): ClientHttp2Session = js.native
+  def connect(authority: URL, options: Http2ConnectOptions, listener: js.Function): ClientHttp2Session    = js.native
 
   def constants: Http2Constants = js.native
 
diff --git a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/http2/Http2Headers.scala b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/http2/Http2Headers.scala
index a320eda4b..43bac459c 100644
--- a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/http2/Http2Headers.scala
+++ b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/http2/Http2Headers.scala
@@ -52,7 +52,9 @@ trait Http2Headers extends js.Object {
   def apply(key: String): js.UndefOr[String | js.Array[String]] = js.native
 
   @JSBracketAccess
-  def update(key: String, value: String | js.Array[String]): Unit = js.native
+  def update(key: String, value: String): Unit = js.native
+  @JSBracketAccess
+  def update(key: String, value: js.Array[String]): Unit = js.native
 }
 
 object Http2Headers {
diff --git a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/http2/Http2ServerResponse.scala b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/http2/Http2ServerResponse.scala
index a41eaf81f..9da8726f2 100644
--- a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/http2/Http2ServerResponse.scala
+++ b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/http2/Http2ServerResponse.scala
@@ -28,12 +28,13 @@ class Http2ServerResponse extends stream.Writable with Http2TimeoutOps {
                          callback: js.Function2[io.scalajs.nodejs.Error, ServerHttp2Stream, Any]
   ): Unit = js.native
 
-  def getHeader(name: String): String                                 = js.native
-  def getHeaderNames(name: String): js.Array[String]                  = js.native
-  def getHeaders(): Http2Headers                                      = js.native
-  def hasHeader(name: String): Boolean                                = js.native
-  def removeHeader(name: String): Unit                                = js.native
-  def setHeader(name: String, value: String | js.Array[String]): Unit = js.native
+  def getHeader(name: String): String                        = js.native
+  def getHeaderNames(name: String): js.Array[String]         = js.native
+  def getHeaders(): Http2Headers                             = js.native
+  def hasHeader(name: String): Boolean                       = js.native
+  def removeHeader(name: String): Unit                       = js.native
+  def setHeader(name: String, value: String): Unit           = js.native
+  def setHeader(name: String, value: js.Array[String]): Unit = js.native
 
   @deprecated("Use writableEnd", "Node.js v13.4.0, v12.16.0")
   def finished: Boolean    = js.native
diff --git a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/http2/Http2Session.scala b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/http2/Http2Session.scala
index 7c31466dd..9fdc2500f 100644
--- a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/http2/Http2Session.scala
+++ b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/http2/Http2Session.scala
@@ -27,13 +27,11 @@ trait Http2Session extends IEventEmitter {
 
   def encrypted: Boolean = js.native
 
-  def goaway(code: Int, lastStreamID: Int, opaqueData: TypedArray[_, _] | DataView): Unit = js.native
-
-  def goaway(code: Int, lastStreamID: Int): Unit = js.native
-
-  def goaway(code: Int): Unit = js.native
-
-  def goaway(): Unit = js.native
+  def goaway(code: Int, lastStreamID: Int, opaqueData: TypedArray[_, _]): Unit = js.native
+  def goaway(code: Int, lastStreamID: Int, opaqueData: DataView): Unit         = js.native
+  def goaway(code: Int, lastStreamID: Int): Unit                               = js.native
+  def goaway(code: Int): Unit                                                  = js.native
+  def goaway(): Unit                                                           = js.native
 
   def localSettings: Http2Settings  = js.native
   def remoteSettings: Http2Settings = js.native
@@ -42,9 +40,9 @@ trait Http2Session extends IEventEmitter {
 
   def pendingSettingsAck: Boolean = js.native
 
-  def ping(payload: TypedArray[_, _] | DataView, callback: js.Function): Boolean = js.native
-
-  def ping(callback: js.Function): Boolean = js.native
+  def ping(payload: TypedArray[_, _], callback: js.Function): Boolean = js.native
+  def ping(payload: DataView, callback: js.Function): Boolean         = js.native
+  def ping(callback: js.Function): Boolean                            = js.native
 
   def ref(): Unit = js.native
 
diff --git a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/http2/ServerHttp2Session.scala b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/http2/ServerHttp2Session.scala
index 95bc2cca2..a162e42e5 100644
--- a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/http2/ServerHttp2Session.scala
+++ b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/http2/ServerHttp2Session.scala
@@ -4,7 +4,8 @@ import scala.scalajs.js
 
 @js.native
 trait ServerHttp2Session extends Http2Session {
-  def altsvc(alt: String, originOrStream: js.|[Int, Origin]): Unit = js.native
+  def altsvc(alt: String, stream: Int): Unit    = js.native
+  def altsvc(alt: String, origin: Origin): Unit = js.native
 
   def origin(origins: Origin*): Unit = js.native
 }
diff --git a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/https/Https.scala b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/https/Https.scala
index a7aca3bd6..ede525845 100644
--- a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/https/Https.scala
+++ b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/https/Https.scala
@@ -36,17 +36,22 @@ trait Https extends js.Object {
   def createServer(options: ServerOptions): Server                               = js.native
   def createServer(): Server                                                     = js.native
 
-  def get(url: String | URL, options: RequestOptions, callback: js.Function1[ServerResponse, Any]): ClientRequest =
-    js.native
-  def get(url: String | URL, callback: js.Function1[ServerResponse, Any]): ClientRequest = js.native
-  def get(options: RequestOptions, callback: js.Function): ClientRequest                 = js.native
-
-  def request(url: String | URL, options: RequestOptions, callback: js.Function1[ServerResponse, Any]): Unit = js.native
-  def request(url: String | URL, options: RequestOptions): Unit                                              = js.native
-  def request(url: String | URL, callback: js.Function1[ServerResponse, Any]): Unit                          = js.native
-  def request(url: String | URL): Unit                                                                       = js.native
-  def request(options: RequestOptions): Unit                                                                 = js.native
-  def request(options: RequestOptions, callback: js.Function1[ServerResponse, Any]): Unit                    = js.native
+  def get(url: String, options: RequestOptions, callback: js.Function1[ServerResponse, Any]): ClientRequest = js.native
+  def get(url: String, callback: js.Function1[ServerResponse, Any]): ClientRequest                          = js.native
+  def get(url: URL, options: RequestOptions, callback: js.Function1[ServerResponse, Any]): ClientRequest    = js.native
+  def get(url: URL, callback: js.Function1[ServerResponse, Any]): ClientRequest                             = js.native
+  def get(options: RequestOptions, callback: js.Function): ClientRequest                                    = js.native
+
+  def request(url: String, options: RequestOptions, callback: js.Function1[ServerResponse, Any]): Unit = js.native
+  def request(url: String, options: RequestOptions): Unit                                              = js.native
+  def request(url: String, callback: js.Function1[ServerResponse, Any]): Unit                          = js.native
+  def request(url: String): Unit                                                                       = js.native
+  def request(url: URL, options: RequestOptions, callback: js.Function1[ServerResponse, Any]): Unit    = js.native
+  def request(url: URL, options: RequestOptions): Unit                                                 = js.native
+  def request(url: URL, callback: js.Function1[ServerResponse, Any]): Unit                             = js.native
+  def request(url: URL): Unit                                                                          = js.native
+  def request(options: RequestOptions): Unit                                                           = js.native
+  def request(options: RequestOptions, callback: js.Function1[ServerResponse, Any]): Unit              = js.native
 }
 
 /**
diff --git a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/https/package.scala b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/https/package.scala
index 408825fa0..6ba894e23 100644
--- a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/https/package.scala
+++ b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/https/package.scala
@@ -43,16 +43,20 @@ package object https {
       promiseCallback1[ServerResponse](https.request(options, _))
     }
 
-    /**
-      * Makes a request to a secure web server.
-      */
     @inline
-    def requestFuture(url: String | URL): Future[ServerResponse] = {
+    def requestFuture(url: String): Future[ServerResponse] = {
       promiseCallback1[ServerResponse](https.request(url, _))
     }
-
     @inline
-    def requestFuture(url: String | URL, options: RequestOptions): Future[ServerResponse] = {
+    def requestFuture(url: URL): Future[ServerResponse] = {
+      promiseCallback1[ServerResponse](https.request(url, _))
+    }
+    @inline
+    def requestFuture(url: String, options: RequestOptions): Future[ServerResponse] = {
+      promiseCallback1[ServerResponse](https.request(url, options, _))
+    }
+    @inline
+    def requestFuture(url: URL, options: RequestOptions): Future[ServerResponse] = {
       promiseCallback1[ServerResponse](https.request(url, options, _))
     }
   }
diff --git a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/process/Process.scala b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/process/Process.scala
index dd2646011..0d37ec550 100644
--- a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/process/Process.scala
+++ b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/process/Process.scala
@@ -275,7 +275,10 @@ trait Process extends IEventEmitter {
     * This is a privileged operation, meaning you need to be root or have the CAP_SETGID capability.
     * @example process.initgroups(user, extra_group)
     */
-  def initgroups(user: String | Int, extra_group: String | Int): js.Array[Int] = js.native
+  def initgroups(user: String, extra_group: String): js.Array[Int] = js.native
+  def initgroups(user: String, extra_group: Int): js.Array[Int]    = js.native
+  def initgroups(user: Int, extra_group: String): js.Array[Int]    = js.native
+  def initgroups(user: Int, extra_group: Int): js.Array[Int]       = js.native
 
   def hasUncaughtExceptionCaptureCallback(): Boolean = js.native
 
@@ -291,8 +294,9 @@ trait Process extends IEventEmitter {
     * like the kill system call. The signal sent may do something other than kill the target process.
     * @example process.kill(pid[, signal])
     */
-  def kill(pid: Int, signal: String | Int): Unit = js.native
-  def kill(pid: Int): Unit                       = js.native
+  def kill(pid: Int, signal: String): Unit = js.native
+  def kill(pid: Int, signal: Int): Unit    = js.native
+  def kill(pid: Int): Unit                 = js.native
 
   /**
     * Returns an object describing the memory usage of the Node.js process measured in bytes.
@@ -335,35 +339,39 @@ trait Process extends IEventEmitter {
     * @example process.setegid(id)
     * @since 2.0.0
     */
-  def setegid(id: String | Int): Unit = js.native
+  def setegid(id: String): Unit = js.native
+  def setegid(id: Int): Unit    = js.native
 
   /**
     * Sets the effective user identity of the process. This accepts either a numerical ID or a username string.
     * If a username is specified, this method blocks while resolving it to a numerical ID.
     * @example process.seteuid(id)
     */
-  def seteuid(id: String | Int): Unit = js.native
+  def seteuid(id: String): Unit = js.native
+  def seteuid(id: Int): Unit    = js.native
 
   /**
     * Sets the group identity of the process. This accepts either a numerical ID or a groupname string.
     * If a groupname is specified, this method blocks while resolving it to a numerical ID.
     * @example process.setgid(id)
     */
-  def setgid(id: String | Int): Unit = js.native
+  def setgid(id: String): Unit = js.native
+  def setgid(id: Int): Unit    = js.native
 
   /**
     * Sets the supplementary group IDs. This is a privileged operation, meaning you need to be root or have the
     * CAP_SETGID capability. The list can contain group IDs, group names or both.
     * @example process.setgroups(groups)
     */
-  def setgroups(groups: js.Array[Int] | js.Array[String] | js.Array[String | Int]): Unit = js.native
+  def setgroups(groups: js.Array[Int]): Unit = js.native
 
   /**
     * Sets the user identity of the process. This accepts either a numerical ID or a username string.
     * If a username is specified, this method blocks while resolving it to a numerical ID.
     * @example process.setuid(id)
     */
-  def setuid(id: String | Int): Unit = js.native
+  def setuid(id: String): Unit = js.native
+  def setuid(id: Int): Unit    = js.native
 
   def setUncaughtExceptionCaptureCallback(callback: js.Function): Unit = js.native
   def setUncaughtExceptionCaptureCallback(): Unit                      = js.native
diff --git a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/repl/REPLServer.scala b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/repl/REPLServer.scala
index a2ab51cc0..0b9095d64 100644
--- a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/repl/REPLServer.scala
+++ b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/repl/REPLServer.scala
@@ -32,7 +32,8 @@ trait REPLServer extends IEventEmitter with Interface {
     * @param keyword The command keyword (without a leading . character).
     * @param cmd     The function to invoke when the command is processed.
     */
-  def defineCommand(keyword: String, cmd: DefinedCommand | js.Function1[String, Any]): Unit = js.native
+  def defineCommand(keyword: String, cmd: DefinedCommand): Unit            = js.native
+  def defineCommand(keyword: String, cmd: js.Function1[String, Any]): Unit = js.native
 
   /**
     * The replServer.displayPrompt() method readies the REPL instance for input from the user, printing the
diff --git a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/stream/Stream.scala b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/stream/Stream.scala
index f3208c409..671eb1782 100644
--- a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/stream/Stream.scala
+++ b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/stream/Stream.scala
@@ -223,7 +223,8 @@ sealed trait IReadable extends LegacyStream {
     * a Transform stream instead.
     * @example readable.unshift(chunk)
     */
-  def unshift(chunk: String | Uint8Array): Unit = js.native
+  def unshift(chunk: String): Unit     = js.native
+  def unshift(chunk: Uint8Array): Unit = js.native
 
   /**
     * Versions of Node.js prior to v0.10 had streams that did not implement the entire Streams API as it is today.
@@ -287,9 +288,10 @@ sealed trait IWritable extends LegacyStream {
 
   def destroyed: Boolean = js.native
 
-  def end(chunk: String | Uint8Array, callback: js.Function1[Error, Any]): this.type = js.native
-  def end(chunk: String | Uint8Array): this.type                                     = js.native
-
+  def end(chunk: String, callback: js.Function1[Error, Any]): this.type                   = js.native
+  def end(chunk: Uint8Array, callback: js.Function1[Error, Any]): this.type               = js.native
+  def end(chunk: String): this.type                                                       = js.native
+  def end(chunk: Uint8Array): this.type                                                   = js.native
   def end(chunk: String, encoding: String, callback: js.Function1[Error, Any]): this.type = js.native
   def end(chunk: String, encoding: String): this.type                                     = js.native
   def end(callback: js.Function1[Error, Any]): this.type                                  = js.native
@@ -323,8 +325,10 @@ sealed trait IWritable extends LegacyStream {
   @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12)
   def writableObjectMode: Boolean = js.native
 
-  def write(chunk: Uint8Array | String, callback: js.Function1[Error, Any]): Boolean      = js.native
-  def write(chunk: Uint8Array | String): Boolean                                          = js.native
+  def write(chunk: Uint8Array, callback: js.Function1[Error, Any]): Boolean               = js.native
+  def write(chunk: Uint8Array): Boolean                                                   = js.native
+  def write(chunk: String, callback: js.Function1[Error, Any]): Boolean                   = js.native
+  def write(chunk: String): Boolean                                                       = js.native
   def write(chunk: String, encoding: String): Boolean                                     = js.native
   def write(chunk: String, encoding: String, callback: js.Function1[Error, Any]): Boolean = js.native
 }
diff --git a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/url/URL.scala b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/url/URL.scala
index c2eee36ca..d5436b456 100644
--- a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/url/URL.scala
+++ b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/url/URL.scala
@@ -13,8 +13,9 @@ import scala.scalajs.js.|
   */
 @js.native
 @JSImport("url", "URL")
-class URL(input: String, base: String | URL) extends js.Object {
-  def this(input: String) = this(input, ???)
+class URL(input: String, base: String) extends js.Object {
+  def this(input: String, base: URL) = this(input, "")
+  def this(input: String) = this(input, "")
 
   /**
     * The auth property is the username and password portion of the URL, also referred to as "userinfo".
@@ -169,7 +170,8 @@ object URL extends js.Object {
     */
   def domainToUnicode(domain: String): String = js.native
 
-  def fileURLToPath(url: URL | String): String = js.native
+  def fileURLToPath(url: URL): String    = js.native
+  def fileURLToPath(url: String): String = js.native
 
   def pathToFileURL(url: String): URL = js.native
 }
diff --git a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/util/TextDecoder.scala b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/util/TextDecoder.scala
index b617ff2cc..db7923e8c 100644
--- a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/util/TextDecoder.scala
+++ b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/util/TextDecoder.scala
@@ -15,8 +15,10 @@ class TextDecoder() extends js.Object {
   val fatal: Boolean     = js.native
   val ignoreBOM: Boolean = js.native
 
-  def decode(buffer: ArrayBuffer | ArrayBufferView, options: TextDecodeOptions): String = js.native
-  def decode(buffer: ArrayBuffer | ArrayBufferView): String                             = js.native
+  def decode(buffer: ArrayBuffer, options: TextDecodeOptions): String     = js.native
+  def decode(buffer: ArrayBufferView, options: TextDecodeOptions): String = js.native
+  def decode(buffer: ArrayBuffer): String                                 = js.native
+  def decode(buffer: ArrayBufferView): String                             = js.native
 }
 
 @Factory
diff --git a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/worker_threads/Worker.scala b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/worker_threads/Worker.scala
index 7f6446c74..eae850446 100644
--- a/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/worker_threads/Worker.scala
+++ b/app/nodejs-v14/src/main/scala/io/scalajs/nodejs/worker_threads/Worker.scala
@@ -1,6 +1,7 @@
 package io.scalajs.nodejs.worker_threads
 
 import scala.scalajs.js
+import scala.scalajs.js.|
 import scala.scalajs.js.annotation.JSImport
 
 @js.native
@@ -16,7 +17,7 @@ class Worker(filename: String, workerOptions: WorkerOptions) extends js.Object w
 
   def threadId: Int = js.native
 
-  def stderr: io.scalajs.nodejs.stream.Readable            = js.native
-  def stdout: io.scalajs.nodejs.stream.Readable            = js.native
-  def stdin: js.|[io.scalajs.nodejs.stream.Writable, Null] = js.native
+  def stderr: io.scalajs.nodejs.stream.Readable       = js.native
+  def stdout: io.scalajs.nodejs.stream.Readable       = js.native
+  def stdin: io.scalajs.nodejs.stream.Writable | Null = js.native
 }