Convert to TypeScript

.babelrc

@@ -1,3 +1,6 @@
 {
-  "presets": [["@babel/preset-env", { "targets": "defaults" }]]
+  "presets": [
+    ["@babel/preset-env", { "targets": "defaults" }],
+    "@babel/preset-typescript"
+  ]
 }

.github/workflows/CI.yml

@@ -19,5 +19,6 @@ jobs:
       - run: npm ci
       - run: npm run build
       - run: npm run test
+      - run: npm run type-check
       - run: npm run lint
       - run: npm run format-check

package.json

@@ -9,7 +9,7 @@
   "browser": "dist/jsondiffpatch.umd.js",
   "main": "dist/jsondiffpatch.cjs.js",
   "module": "dist/jsondiffpatch.esm.js",
-  "types": "./dist/index",
+  "types": "dist/index.d.ts",
   "files": [
     "dist",
     "bin"
@@ -23,6 +23,7 @@
     "test": "jest --coverage",
     "format": "prettier . --write",
     "format-check": "prettier . --check",
+    "type-check": "tsc",
     "prepack": "npm run build",
     "prepublishOnly": "npm run test && npm run lint"
   },
@@ -43,6 +44,7 @@
     "@babel/core": "^7.22.10",
     "@babel/eslint-parser": "^7.22.10",
     "@babel/preset-env": "^7.22.10",
+    "@babel/preset-typescript": "^7.22.11",
     "@rollup/plugin-babel": "^6.0.3",
     "@rollup/plugin-commonjs": "^25.0.4",
     "@rollup/plugin-node-resolve": "^15.2.0",
@@ -54,7 +56,8 @@
     "jest": "^29.6.2",
     "prettier": "^3.0.2",
     "rollup": "^3.28.0",
-    "rollup-plugin-visualizer": "^5.9.2"
+    "rollup-plugin-visualizer": "^5.9.2",
+    "typescript": "~5.1.6"
   },
   "license": "MIT",
   "engines": {

rollup.config.mjs

@@ -9,12 +9,11 @@ import { visualizer } from 'rollup-plugin-visualizer';
 
 import pkg from './package.json' assert { type: 'json' };
 
-const copySrcFileToDist = copyFromFolderToDist('src');
 const copyDocsFileToDist = copyFromFolderToDist('docs');
 
 export default [
   {
-    input: 'src/main.js',
+    input: 'src/index.ts',
     external: ['chalk'],
     output: {
       name: pkg.name,
@@ -32,13 +31,14 @@ export default [
       babel({
         exclude: 'node_modules/**',
         babelHelpers: 'bundled',
+        extensions: ['.js', '.jsx', '.es6', '.es', '.mjs', '.ts'],
       }),
-      resolve(), // so Rollup can find node modules
-      commonjs(), // so Rollup can convert node modules to ES modules
+      resolve({ extensions: ['.mjs', '.js', '.json', '.node', '.ts'] }),
+      commonjs(),
     ],
   },
   {
-    input: 'src/main.js',
+    input: 'src/index.ts',
     external: ['chalk', 'diff-match-patch'],
     output: {
       name: pkg.name,
@@ -61,13 +61,14 @@ export default [
       babel({
         exclude: 'node_modules/**',
         babelHelpers: 'bundled',
+        extensions: ['.js', '.jsx', '.es6', '.es', '.mjs', '.ts'],
       }),
-      resolve(), // so Rollup can find node modules
-      commonjs(), // so Rollup can convert node modules to ES modules
+      resolve({ extensions: ['.mjs', '.js', '.json', '.node', '.ts'] }),
+      commonjs(),
     ],
   },
   {
-    input: 'src/main.js',
+    input: 'src/index.ts',
     external: [
       // external node modules
       'diff-match-patch',
@@ -77,8 +78,9 @@ export default [
       babel({
         exclude: 'node_modules/**',
         babelHelpers: 'bundled',
+        extensions: ['.js', '.jsx', '.es6', '.es', '.mjs', '.ts'],
       }),
-      copySrcFileToDist('index.d.ts'),
+      resolve({ extensions: ['.mjs', '.js', '.json', '.node', '.ts'] }),
       copyDocsFileToDist('formatters-styles/annotated.css'),
       copyDocsFileToDist('formatters-styles/html.css'),
     ],

src/clone.js → src/clone.ts

@@ -1,21 +1,16 @@
-const isArray =
-  typeof Array.isArray === 'function'
-    ? Array.isArray
-    : (a) => a instanceof Array;
-
-function cloneRegExp(re) {
-  const regexMatch = /^\/(.*)\/([gimyu]*)$/.exec(re.toString());
+function cloneRegExp(re: RegExp) {
+  const regexMatch = /^\/(.*)\/([gimyu]*)$/.exec(re.toString())!;
   return new RegExp(regexMatch[1], regexMatch[2]);
 }
 
-export default function clone(arg) {
+export default function clone(arg: unknown): unknown {
   if (typeof arg !== 'object') {
     return arg;
   }
   if (arg === null) {
     return null;
   }
-  if (isArray(arg)) {
+  if (Array.isArray(arg)) {
     return arg.map(clone);
   }
   if (arg instanceof Date) {
@@ -27,7 +22,9 @@ export default function clone(arg) {
   const cloned = {};
   for (const name in arg) {
     if (Object.prototype.hasOwnProperty.call(arg, name)) {
-      cloned[name] = clone(arg[name]);
+      (cloned as { [name: string]: unknown })[name] = clone(
+        (arg as { [name: string]: unknown })[name],
+      );
     }
   }
   return cloned;

src/contexts/context.js → src/contexts/context.ts

@@ -1,7 +1,21 @@
 import Pipe from '../pipe';
+import { Options } from '../processor';
 
-export default class Context {
-  setResult(result) {
+export default class Context<TResult> {
+  result?: TResult;
+  hasResult?: boolean;
+  exiting?: boolean;
+  nextPipe?: string | Pipe<this>;
+  parent?: this;
+  childName?: string | number;
+  root?: this;
+  options?: Options;
+  children?: this[];
+  nextAfterChildren?: this | null;
+  next?: this | null;
+  pipe?: string;
+
+  setResult(result: TResult) {
     this.result = result;
     this.hasResult = true;
     return this;
@@ -12,7 +26,9 @@ export default class Context {
     return this;
   }
 
-  switchTo(next, pipe) {
+  switchTo(next: string | Pipe<this>): this;
+  switchTo(next: this, pipe?: string | Pipe<this>): this;
+  switchTo(next: string | Pipe<this> | this, pipe?: string | Pipe<this>) {
     if (typeof next === 'string' || next instanceof Pipe) {
       this.nextPipe = next;
     } else {
@@ -24,7 +40,7 @@ export default class Context {
     return this;
   }
 
-  push(child, name) {
+  push(child: this, name: string | number) {
     child.parent = this;
     if (typeof name !== 'undefined') {
       child.childName = name;