feat: add type definitions

package.json

@@ -12,11 +12,13 @@
     "url": "https://opencollective.com/webpack"
   },
   "main": "dist/cjs.js",
+  "types": "types/index.d.ts",
   "engines": {
     "node": ">= 12.13.0"
   },
   "scripts": {
     "start": "npm run build -- -w",
+    "build:types": "tsc --declaration --emitDeclarationOnly --outDir types && prettier \"types/**/*.ts\" --write",
     "clean": "del-cli dist",
     "prebuild": "npm run clean",
     "build": "cross-env NODE_ENV=production babel src -d dist --copy-files",
@@ -34,13 +36,15 @@
     "release": "standard-version"
   },
   "files": [
-    "dist"
+    "dist",
+    "types"
   ],
   "peerDependencies": {
     "webpack": "^5.0.0"
   },
   "dependencies": {
-    "source-map": "^0.6.1"
+    "source-map": "^0.6.1",
+    "typescript": "^4.6.4"
   },
   "devDependencies": {
     "@babel/cli": "^7.17.10",

src/index.js

@@ -9,8 +9,26 @@ import { getExports, renderExports } from "./utils";
 
 const FOOTER = "/*** EXPORTS FROM exports-loader ***/\n";
 
+/** @typedef {import("source-map").RawSourceMap} RawSourceMap */
+/** @typedef {import("schema-utils/declarations/validate").Schema} Schema */
+
+/**
+ * @template T
+ * @typedef {Object} LoaderOptions<T>Allows to choose how errors are displayed.
+ * @property {"commonjs" | "module"} [type]
+ * @property {string| object | string[] | object[]} exports
+ */
+
+/**
+ * The exports loader allows to setup exports
+ * @template T
+ * @this {import("webpack").LoaderContext<LoaderOptions<T>>}
+ * @param {string} content
+ * @param { RawSourceMap } sourceMap
+ */
+
 export default function loader(content, sourceMap) {
-  const options = this.getOptions(schema);
+  const options = this.getOptions(/** @type {Schema} */ (schema));
   const type = options.type || "module";
   const callback = this.async();
 
@@ -19,7 +37,7 @@ export default function loader(content, sourceMap) {
   try {
     exports = getExports(type, options.exports);
   } catch (error) {
-    callback(error);
+    callback(/** @type {Error | null | undefined} */ (error));
 
     return;
   }
@@ -36,10 +54,12 @@ export default function loader(content, sourceMap) {
 
     const result = node.toStringWithSourceMap({ file: this.resourcePath });
 
+    // @ts-ignore map only has toString() method in types
     callback(null, result.code, result.map.toJSON());
 
     return;
   }
 
+  // @ts-ignore sourceMap in the webpack doesn't have the type RawSourceMap
   callback(null, `${content}\n${FOOTER}${exportsCode}`, sourceMap);
 }

src/utils.js

@@ -1,9 +1,47 @@
+/** @typedef {import("source-map").RawSourceMap} RawSourceMap */
+
+/**
+ * @template T
+ * @typedef {Object} LoaderOptions<T>
+ * @property {string} [type]
+ * @property {string| object | string[] | object[]} [exports]
+ */
+
+/**
+ * The exports loader allows to setup exports
+ * @template T
+ * @typedef {import("webpack").LoaderContext<LoaderOptions<T>>} LoaderOption
+ * @param {string} content
+ * @param { RawSourceMap } sourceMap
+ */
+
+/**
+ * @typedef {Object} Identifier
+ * @property {string} type
+ * @property {string} [value]
+ */
+
+/**
+ * @typedef {Object} Export
+ * @property {string} syntax
+ * @property {string} [name]
+ * @property {string} [alias]
+ */
+
+/**
+ *
+ * @param {string | object | string[] | Object[]} item
+ * @returns
+ */
 function forError(item) {
   return typeof item === "string"
     ? item
     : `\n${JSON.stringify(item, null, " ")}\n`;
 }
 
+/**
+ * @param {string} command
+ */
 function splitCommand(command) {
   const result = command
     .split("|")
@@ -21,8 +59,13 @@ function splitCommand(command) {
   return result;
 }
 
+/**
+ *
+ * @param {string} type
+ * @param {string | object | string[] | Object[] } item
+ */
 function resolveExports(type, item) {
-  let result;
+  let /** @type {Export} */ result;
 
   if (typeof item === "string") {
     const noWhitespaceItem = item.trim();
@@ -97,8 +140,12 @@ function resolveExports(type, item) {
   return result;
 }
 
+/**
+ *
+ * @param {Array<Export>} array
+ */
 function getIdentifiers(array) {
-  return array.reduce((accumulator, item) => {
+  return array.reduce((/** @type {Array<Identifier>} */ accumulator, item) => {
     if (typeof item.alias !== "undefined") {
       accumulator.push({ type: "alias", value: item.alias });
 
@@ -111,6 +158,12 @@ function getIdentifiers(array) {
   }, []);
 }
 
+/**
+ *
+ * @param {string} type
+ * @param {string| object | string[] | object[]} exports
+ * @returns
+ */
 function getExports(type, exports) {
   let result;
   const exportItems =
@@ -142,7 +195,10 @@ function getExports(type, exports) {
   if (duplicates.length > 0) {
     throw new Error(
       `Duplicate ${duplicates
-        .map((identifier) => `"${identifier.value}" (as "${identifier.type}")`)
+        .map(
+          (/** @type {Identifier} */ identifier) =>
+            `"${identifier.value}" (as "${identifier.type}")`
+        )
         .join(", ")} identifiers found in "\n${JSON.stringify(
         exports,
         null,
@@ -154,6 +210,12 @@ function getExports(type, exports) {
   return result;
 }
 
+/**
+ *
+ * @param {Identifier[]} array
+ * @param {"value"} key
+ * @returns
+ */
 function duplicateBy(array, key) {
   return array.filter(
     (a, aIndex) =>
@@ -162,6 +224,13 @@ function duplicateBy(array, key) {
   );
 }
 
+/**
+ * @template T
+ * @param {LoaderOption<T>} loaderContext
+ * @param {"commonjs"|"module"} type
+ * @param {Array<Export>} exports
+ * @returns
+ */
 function renderExports(loaderContext, type, exports) {
   let code = "";
 

tsconfig.json

@@ -0,0 +1,14 @@
+{
+  "compilerOptions": {
+    "target": "esnext",
+    "moduleResolution": "node",
+    "allowJs": true,
+    "checkJs": true,
+    "strict": true,
+    "types": ["node"],
+    "resolveJsonModule": true,
+    "newLine": "LF",
+    "allowSyntheticDefaultImports": true
+  },
+  "include": ["./src/**/*"]
+}

types/cjs.d.ts

@@ -0,0 +1,3 @@
+declare const _exports: typeof loader.default;
+export = _exports;
+import loader = require("./index");

types/index.d.ts

@@ -0,0 +1,29 @@
+/** @typedef {import("source-map").RawSourceMap} RawSourceMap */
+/** @typedef {import("schema-utils/declarations/validate").Schema} Schema */
+/**
+ * @template T
+ * @typedef {Object} LoaderOptions<T>Allows to choose how errors are displayed.
+ * @property {"commonjs" | "module"} [type]
+ * @property {string| object | string[] | object[]} exports
+ */
+/**
+ * The exports loader allows to setup exports
+ * @template T
+ * @this {import("webpack").LoaderContext<LoaderOptions<T>>}
+ * @param {string} content
+ * @param { RawSourceMap } sourceMap
+ */
+export default function loader<T>(
+  this: import("webpack").LoaderContext<LoaderOptions<T>>,
+  content: string,
+  sourceMap: RawSourceMap
+): void;
+export type RawSourceMap = import("source-map").RawSourceMap;
+export type Schema = import("schema-utils/declarations/validate").Schema;
+/**
+ * <T>Allows to choose how errors are displayed.
+ */
+export type LoaderOptions<T> = {
+  type?: "module" | "commonjs" | undefined;
+  exports: string | object | string[] | object[];
+};

types/utils.d.ts

@@ -0,0 +1,43 @@
+export type RawSourceMap = import("source-map").RawSourceMap;
+/**
+ * <T>
+ */
+export type LoaderOptions<T> = {
+  type?: string | undefined;
+  exports?: string | object | string[] | object[] | undefined;
+};
+/**
+ * The exports loader allows to setup exports
+ */
+export type LoaderOption<T> = import("webpack").LoaderContext<LoaderOptions<T>>;
+export type Identifier = {
+  type: string;
+  value?: string | undefined;
+};
+export type Export = {
+  syntax: string;
+  name?: string | undefined;
+  alias?: string | undefined;
+};
+/**
+ *
+ * @param {string} type
+ * @param {string| object | string[] | object[]} exports
+ * @returns
+ */
+export function getExports(
+  type: string,
+  exports: string | object | string[] | object[]
+): Export[];
+/**
+ * @template T
+ * @param {LoaderOption<T>} loaderContext
+ * @param {"commonjs"|"module"} type
+ * @param {Array<Export>} exports
+ * @returns
+ */
+export function renderExports<T>(
+  loaderContext: import("webpack").LoaderContext<LoaderOptions<T>>,
+  type: "commonjs" | "module",
+  exports: Array<Export>
+): string;