Merge pull request #8895 from Microsoft/strip_extension

Allow an import of "foo.js" to be matched by a file "foo.ts"

Author: Andy

src/compiler/core.ts

@@ -849,13 +849,22 @@ namespace ts {
     const extensionsToRemove = [".d.ts", ".ts", ".js", ".tsx", ".jsx"];
     export function removeFileExtension(path: string): string {
         for (const ext of extensionsToRemove) {
-            if (fileExtensionIs(path, ext)) {
-                return path.substr(0, path.length - ext.length);
+            const extensionless = tryRemoveExtension(path, ext);
+            if (extensionless !== undefined) {
+                return extensionless;
             }
         }
         return path;
     }
 
+    export function tryRemoveExtension(path: string, extension: string): string {
+        return fileExtensionIs(path, extension) ? path.substring(0, path.length - extension.length) : undefined;
+    }
+
+    export function isJsxOrTsxExtension(ext: string): boolean {
+        return ext === ".jsx" || ext === ".tsx";
+    }
+
     export interface ObjectAllocator {
         getNodeConstructor(): new (kind: SyntaxKind, pos?: number, end?: number) => Node;
         getSourceFileConstructor(): new (kind: SyntaxKind, pos?: number, end?: number) => SourceFile;

src/compiler/diagnosticMessages.json

@@ -2772,6 +2772,10 @@
         "category": "Error",
         "code": 6131
     },
+    "File name '{0}' has a '{1}' extension - stripping it": {
+        "category": "Message",
+        "code": 6132
+    },
 
     "Variable '{0}' implicitly has an '{1}' type.": {
         "category": "Error",

src/compiler/program.ts

@@ -619,8 +619,25 @@ namespace ts {
      * in cases when we know upfront that all load attempts will fail (because containing folder does not exists) however we still need to record all failed lookup locations.
      */
     function loadModuleFromFile(candidate: string, extensions: string[], failedLookupLocation: string[], onlyRecordFailures: boolean, state: ModuleResolutionState): string {
+        // First try to keep/add an extension: importing "./foo.ts" can be matched by a file "./foo.ts", and "./foo" by "./foo.d.ts"
+        const resolvedByAddingOrKeepingExtension = loadModuleFromFileWorker(candidate, extensions, failedLookupLocation, onlyRecordFailures, state);
+        if (resolvedByAddingOrKeepingExtension) {
+            return resolvedByAddingOrKeepingExtension;
+        }
+        // Then try stripping a ".js" or ".jsx" extension and replacing it with a TypeScript one, e.g. "./foo.js" can be matched by "./foo.ts" or "./foo.d.ts"
+        if (hasJavaScriptFileExtension(candidate)) {
+            const extensionless = removeFileExtension(candidate);
+            if (state.traceEnabled) {
+                const extension = candidate.substring(extensionless.length);
+                trace(state.host, Diagnostics.File_name_0_has_a_1_extension_stripping_it, candidate, extension);
+            }
+            return loadModuleFromFileWorker(extensionless, extensions, failedLookupLocation, onlyRecordFailures, state);
+        }
+    }
+
+    function loadModuleFromFileWorker(candidate: string, extensions: string[], failedLookupLocation: string[], onlyRecordFailures: boolean, state: ModuleResolutionState): string {
         if (!onlyRecordFailures) {
-            // check if containig folder exists - if it doesn't then just record failures for all supported extensions without disk probing
+            // check if containing folder exists - if it doesn't then just record failures for all supported extensions without disk probing
             const directory = getDirectoryPath(candidate);
             if (directory) {
                 onlyRecordFailures = !directoryProbablyExists(directory, state.host);
@@ -629,7 +646,7 @@ namespace ts {
         return forEach(extensions, tryLoad);
 
         function tryLoad(ext: string): string {
-            if (ext === ".tsx" && state.skipTsx) {
+            if (state.skipTsx && isJsxOrTsxExtension(ext)) {
                 return undefined;
             }
             const fileName = fileExtensionIs(candidate, ext) ? candidate : candidate + ext;

tests/baselines/reference/moduleResolutionWithExtensions.js

@@ -0,0 +1,46 @@
+//// [tests/cases/conformance/externalModules/moduleResolutionWithExtensions.ts] ////
+
+//// [a.ts]
+
+export default 0;
+
+// No extension: '.ts' added
+//// [b.ts]
+import a from './a';
+
+// Matching extension
+//// [c.ts]
+import a from './a.ts';
+
+// '.js' extension: stripped and replaced with '.ts'
+//// [d.ts]
+import a from './a.js';
+
+//// [jquery.d.ts]
+declare var x: number;
+export default x;
+
+// No extension: '.d.ts' added
+//// [jquery_user_1.ts]
+import j from "./jquery";
+
+// '.js' extension: stripped and replaced with '.d.ts'
+//// [jquery_user_1.ts]
+import j from "./jquery.js"
+
+
+//// [a.js]
+"use strict";
+exports.__esModule = true;
+exports["default"] = 0;
+// No extension: '.ts' added 
+//// [b.js]
+"use strict";
+// Matching extension 
+//// [c.js]
+"use strict";
+// '.js' extension: stripped and replaced with '.ts' 
+//// [d.js]
+"use strict";
+//// [jquery_user_1.js]
+"use strict";

tests/baselines/reference/moduleResolutionWithExtensions.symbols

@@ -0,0 +1,37 @@
+=== /src/a.ts ===
+
+No type information for this code.export default 0;
+No type information for this code.
+No type information for this code.// No extension: '.ts' added
+No type information for this code.=== /src/b.ts ===
+import a from './a';
+>a : Symbol(a, Decl(b.ts, 0, 6))
+
+// Matching extension
+=== /src/c.ts ===
+import a from './a.ts';
+>a : Symbol(a, Decl(c.ts, 0, 6))
+
+// '.js' extension: stripped and replaced with '.ts'
+=== /src/d.ts ===
+import a from './a.js';
+>a : Symbol(a, Decl(d.ts, 0, 6))
+
+=== /src/jquery.d.ts ===
+declare var x: number;
+>x : Symbol(x, Decl(jquery.d.ts, 0, 11))
+
+export default x;
+>x : Symbol(x, Decl(jquery.d.ts, 0, 11))
+
+// No extension: '.d.ts' added
+=== /src/jquery_user_1.ts ===
+import j from "./jquery";
+>j : Symbol(j, Decl(jquery_user_1.ts, 0, 6))
+
+// '.js' extension: stripped and replaced with '.d.ts'
+=== /src/jquery_user_1.ts ===
+import j from "./jquery.js"
+>j : Symbol(j, Decl(jquery_user_1.ts, 0, 6))
+>j : Symbol(j, Decl(jquery_user_1.ts, 0, 6))
+

tests/baselines/reference/moduleResolutionWithExtensions.trace.json

@@ -0,0 +1,32 @@
+[
+    "======== Resolving module './a' from '/src/b.ts'. ========",
+    "Module resolution kind is not specified, using 'NodeJs'.",
+    "Loading module as file / folder, candidate module location '/src/a'.",
+    "File '/src/a.ts' exist - use it as a name resolution result.",
+    "======== Module name './a' was successfully resolved to '/src/a.ts'. ========",
+    "======== Resolving module './a.ts' from '/src/c.ts'. ========",
+    "Module resolution kind is not specified, using 'NodeJs'.",
+    "Loading module as file / folder, candidate module location '/src/a.ts'.",
+    "File '/src/a.ts' exist - use it as a name resolution result.",
+    "======== Module name './a.ts' was successfully resolved to '/src/a.ts'. ========",
+    "======== Resolving module './a.js' from '/src/d.ts'. ========",
+    "Module resolution kind is not specified, using 'NodeJs'.",
+    "Loading module as file / folder, candidate module location '/src/a.js'.",
+    "File '/src/a.js.ts' does not exist.",
+    "File '/src/a.js.tsx' does not exist.",
+    "File '/src/a.js.d.ts' does not exist.",
+    "File name '/src/a.js' has a '.js' extension - stripping it",
+    "File '/src/a.ts' exist - use it as a name resolution result.",
+    "======== Module name './a.js' was successfully resolved to '/src/a.ts'. ========",
+    "======== Resolving module './jquery.js' from '/src/jquery_user_1.ts'. ========",
+    "Module resolution kind is not specified, using 'NodeJs'.",
+    "Loading module as file / folder, candidate module location '/src/jquery.js'.",
+    "File '/src/jquery.js.ts' does not exist.",
+    "File '/src/jquery.js.tsx' does not exist.",
+    "File '/src/jquery.js.d.ts' does not exist.",
+    "File name '/src/jquery.js' has a '.js' extension - stripping it",
+    "File '/src/jquery.ts' does not exist.",
+    "File '/src/jquery.tsx' does not exist.",
+    "File '/src/jquery.d.ts' exist - use it as a name resolution result.",
+    "======== Module name './jquery.js' was successfully resolved to '/src/jquery.d.ts'. ========"
+]

tests/baselines/reference/moduleResolutionWithExtensions.types

@@ -0,0 +1,37 @@
+=== /src/a.ts ===
+
+No type information for this code.export default 0;
+No type information for this code.
+No type information for this code.// No extension: '.ts' added
+No type information for this code.=== /src/b.ts ===
+import a from './a';
+>a : number
+
+// Matching extension
+=== /src/c.ts ===
+import a from './a.ts';
+>a : number
+
+// '.js' extension: stripped and replaced with '.ts'
+=== /src/d.ts ===
+import a from './a.js';
+>a : number
+
+=== /src/jquery.d.ts ===
+declare var x: number;
+>x : number
+
+export default x;
+>x : number
+
+// No extension: '.d.ts' added
+=== /src/jquery_user_1.ts ===
+import j from "./jquery";
+>j : number
+
+// '.js' extension: stripped and replaced with '.d.ts'
+=== /src/jquery_user_1.ts ===
+import j from "./jquery.js"
+>j : number
+>j : number
+

tests/baselines/reference/nameWithFileExtension.errors.txt

@@ -8,6 +8,9 @@ import foo = require('./foo_0.js');
 var x = foo.foo + 42;
 
 
+//// [foo_0.js]
+"use strict";
+exports.foo = 42;
 //// [foo_1.js]
 "use strict";
 var foo = require('./foo_0.js');

tests/baselines/reference/nameWithFileExtension.js

@@ -0,0 +1,14 @@
+=== tests/cases/conformance/externalModules/foo_1.ts ===
+import foo = require('./foo_0.js');
+>foo : Symbol(foo, Decl(foo_1.ts, 0, 0))
+
+var x = foo.foo + 42;
+>x : Symbol(x, Decl(foo_1.ts, 1, 3))
+>foo.foo : Symbol(foo.foo, Decl(foo_0.ts, 0, 10))
+>foo : Symbol(foo, Decl(foo_1.ts, 0, 0))
+>foo : Symbol(foo.foo, Decl(foo_0.ts, 0, 10))
+
+=== tests/cases/conformance/externalModules/foo_0.ts ===
+export var foo = 42;
+>foo : Symbol(foo, Decl(foo_0.ts, 0, 10))
+