Add ECMAScript method shorthand support to webpack5-module-minifier-plugin

common/changes/@rushstack/webpack5-module-minifier-plugin/copilot-webpack-shorthand-support_2026-02-11-23-38.json

@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@rushstack/webpack5-module-minifier-plugin",
+      "comment": "Add support for webpack's ECMAScript method shorthand format. The plugin now detects when modules are emitted using method shorthand syntax (without 'function' keyword or arrow syntax) and wraps them appropriately for minification.",
+      "type": "minor"
+    }
+  ],
+  "packageName": "@rushstack/webpack5-module-minifier-plugin"
+}

common/reviews/api/webpack5-module-minifier-plugin.api.md

@@ -59,6 +59,7 @@ export interface IFactoryMeta {
 // @public
 export interface IModuleInfo {
     id: string | number;
+    isShorthand?: boolean;
     module: Module;
     source: sources.Source;
 }
@@ -110,6 +111,12 @@ export interface IRenderedModulePosition {
 // @public
 export const MODULE_WRAPPER_PREFIX: '__MINIFY_MODULE__(';
 
+// @public
+export const MODULE_WRAPPER_SHORTHAND_PREFIX: string;
+
+// @public
+export const MODULE_WRAPPER_SHORTHAND_SUFFIX: string;
+
 // @public
 export const MODULE_WRAPPER_SUFFIX: ');';
 

webpack/webpack5-module-minifier-plugin/src/Constants.ts

@@ -14,6 +14,23 @@ export const MODULE_WRAPPER_PREFIX: '__MINIFY_MODULE__(' = '__MINIFY_MODULE__(';
  */
 export const MODULE_WRAPPER_SUFFIX: ');' = ');';
 
+/**
+ * Prefix to wrap ECMAScript method shorthand `(module, __webpack_exports__, __webpack_require__) { ... }` so that the minifier doesn't delete it.
+ * Used when webpack emits modules using shorthand syntax.
+ * Combined with the suffix, creates: `__MINIFY_MODULE__({__DEFAULT_ID__(params){body}});`
+ * Public because alternate Minifier implementations may wish to know about it.
+ * @public
+ */
+export const MODULE_WRAPPER_SHORTHAND_PREFIX: string = `${MODULE_WRAPPER_PREFIX}{__DEFAULT_ID__`;
+/**
+ * Suffix to wrap ECMAScript method shorthand `(module, __webpack_exports__, __webpack_require__) { ... }` so that the minifier doesn't delete it.
+ * Used when webpack emits modules using shorthand syntax.
+ * Combined with the prefix, creates: `__MINIFY_MODULE__({__DEFAULT_ID__(params){body}});`
+ * Public because alternate Minifier implementations may wish to know about it.
+ * @public
+ */
+export const MODULE_WRAPPER_SHORTHAND_SUFFIX: string = `}${MODULE_WRAPPER_SUFFIX}`;
+
 /**
  * Token preceding a module id in the emitted asset so the minifier can operate on the Webpack runtime or chunk boilerplate in isolation
  * @public
@@ -22,9 +39,14 @@ export const CHUNK_MODULE_TOKEN: '__WEBPACK_CHUNK_MODULE__' = '__WEBPACK_CHUNK_M
 
 /**
  * RegExp for replacing chunk module placeholders
+ * Handles three possible representations:
+ * - `"id":__WEBPACK_CHUNK_MODULE__HASH__` (methodShorthand: false, object)
+ * - `__WEBPACK_CHUNK_MODULE__HASH__` (array syntax)
+ * - `"id":__WEBPACK_CHUNK_MODULE__HASH__` with leading ':' (methodShorthand: true, object)
+ * Captures optional leading `:` to handle shorthand format properly
  * @public
  */
-export const CHUNK_MODULE_REGEX: RegExp = /__WEBPACK_CHUNK_MODULE__([A-Za-z0-9$_]+)/g;
+export const CHUNK_MODULE_REGEX: RegExp = /(:?)__WEBPACK_CHUNK_MODULE__([A-Za-z0-9$_]+)/g;
 
 /**
  * Stage # to use when this should be the first tap in the hook

webpack/webpack5-module-minifier-plugin/src/ModuleMinifierPlugin.ts

@@ -29,6 +29,8 @@ import {
   CHUNK_MODULE_TOKEN,
   MODULE_WRAPPER_PREFIX,
   MODULE_WRAPPER_SUFFIX,
+  MODULE_WRAPPER_SHORTHAND_PREFIX,
+  MODULE_WRAPPER_SHORTHAND_SUFFIX,
   STAGE_BEFORE,
   STAGE_AFTER
 } from './Constants';
@@ -74,6 +76,7 @@ interface IOptionsForHash extends Omit<IModuleMinifierPluginOptions, 'minifier'>
 interface ISourceCacheEntry {
   source: sources.Source;
   hash: string;
+  isShorthand: boolean;
 }
 
 const compilationMetadataMap: WeakMap<Compilation, IModuleMinifierPluginStats> = new WeakMap();
@@ -125,6 +128,46 @@ function isLicenseComment(comment: Comment): boolean {
   return LICENSE_COMMENT_REGEX.test(comment.value);
 }
 
+/**
+ * RegExp for detecting function keyword with optional whitespace
+ */
+const FUNCTION_KEYWORD_REGEX: RegExp = /function\s*\(/;
+
+/**
+ * Detects if the module code uses ECMAScript method shorthand format.
+ * Shorthand format would appear when webpack emits object methods without function keyword
+ * For example: `id(params) { body }` instead of `id: function(params) { body }`
+ *
+ * Following the problem statement's recommendation: inspect the rendered code prior to the first `{`
+ * and look for either a `=>` or `function(`. If neither are encountered, assume object shorthand format.
+ *
+ * @param code - The module source code to check
+ * @returns true if the code is in method shorthand format
+ */
+function isMethodShorthandFormat(code: string): boolean {
+  // Find the position of the first opening brace
+  const firstBraceIndex: number = code.indexOf('{');
+  if (firstBraceIndex === -1) {
+    // No brace found, not a function format
+    return false;
+  }
+
+  // Get the code before the first brace
+  const beforeBrace: string = code.slice(0, firstBraceIndex);
+
+  // Check if it contains '=>' or 'function('
+  // If it does, it's a regular arrow function or function expression, not shorthand
+  // Use a simple check that handles common whitespace variations
+  if (beforeBrace.includes('=>') || FUNCTION_KEYWORD_REGEX.test(beforeBrace)) {
+    return false;
+  }
+
+  // If neither '=>' nor 'function(' are found, assume object method shorthand format
+  // ECMAScript method shorthand is used in object literals: { methodName(params){body} }
+  // Webpack emits this as just (params){body} which only works in the object literal context
+  return true;
+}
+
 /**
  * Webpack plugin that minifies code on a per-module basis rather than per-asset. The actual minification is handled by the input `minifier` object.
  * @public
@@ -333,12 +376,16 @@ export class ModuleMinifierPlugin implements WebpackPluginInstance {
             return cachedResult.source;
           }
 
+          // Get the source code to check its format
+          const sourceCode: string = source.source().toString();
+
+          // Detect if this is ECMAScript method shorthand format
+          const isShorthand: boolean = isMethodShorthandFormat(sourceCode);
+
           // If this module is wrapped in a factory, need to add boilerplate so that the minifier keeps the function
-          const wrapped: sources.Source = new ConcatSource(
-            MODULE_WRAPPER_PREFIX + '\n',
-            source,
-            '\n' + MODULE_WRAPPER_SUFFIX
-          );
+          const wrapped: sources.Source = isShorthand
+            ? new ConcatSource(MODULE_WRAPPER_SHORTHAND_PREFIX, source, MODULE_WRAPPER_SHORTHAND_SUFFIX)
+            : new ConcatSource(MODULE_WRAPPER_PREFIX + '\n', source, '\n' + MODULE_WRAPPER_SUFFIX);
 
           const nameForMap: string = `(modules)/${id}`;
 
@@ -386,8 +433,18 @@ export class ModuleMinifierPlugin implements WebpackPluginInstance {
                     const len: number = minified.length;
 
                     // Trim off the boilerplate used to preserve the factory
-                    unwrapped.replace(0, MODULE_WRAPPER_PREFIX.length - 1, '');
-                    unwrapped.replace(len - MODULE_WRAPPER_SUFFIX.length, len - 1, '');
+                    // Use different prefix/suffix lengths for shorthand vs regular format
+                    // Capture isShorthand from closure instead of looking it up
+                    if (isShorthand) {
+                      // For shorthand format: __MINIFY_MODULE__({__DEFAULT_ID__(args){...}});
+                      // Remove prefix and suffix by their lengths
+                      unwrapped.replace(0, MODULE_WRAPPER_SHORTHAND_PREFIX.length - 1, '');
+                      unwrapped.replace(len - MODULE_WRAPPER_SHORTHAND_SUFFIX.length, len - 1, '');
+                    } else {
+                      // Regular format: __MINIFY_MODULE__(function(args){...}); or __MINIFY_MODULE__((args)=>{...});
+                      unwrapped.replace(0, MODULE_WRAPPER_PREFIX.length - 1, '');
+                      unwrapped.replace(len - MODULE_WRAPPER_SUFFIX.length, len - 1, '');
+                    }
 
                     const withIds: sources.Source = postProcessCode(unwrapped, {
                       compilation,
@@ -402,7 +459,8 @@ export class ModuleMinifierPlugin implements WebpackPluginInstance {
                     minifiedModules.set(hash, {
                       source: cached,
                       module: mod,
-                      id
+                      id,
+                      isShorthand
                     });
                   } catch (err) {
                     compilation.errors.push(err);
@@ -414,10 +472,15 @@ export class ModuleMinifierPlugin implements WebpackPluginInstance {
             );
           }
 
-          const result: sources.Source = new RawSource(`${CHUNK_MODULE_TOKEN}${hash}`);
+          // Create token with optional ':' prefix for shorthand modules
+          // For non-shorthand: __WEBPACK_CHUNK_MODULE__hash (becomes "id":__WEBPACK_CHUNK_MODULE__hash in object)
+          // For shorthand: :__WEBPACK_CHUNK_MODULE__hash (becomes "id"__WEBPACK_CHUNK_MODULE__hash, ':' makes it valid property assignment)
+          const tokenPrefix: string = isShorthand ? ':' : '';
+          const result: sources.Source = new RawSource(`${tokenPrefix}${CHUNK_MODULE_TOKEN}${hash}`);
           sourceCache.set(source, {
             hash,
-            source: result
+            source: result,
+            isShorthand
           });
 
           // Return an expression to replace later

webpack/webpack5-module-minifier-plugin/src/ModuleMinifierPlugin.types.ts

@@ -74,6 +74,11 @@ export interface IModuleInfo {
    * The id of the module, from the chunk graph.
    */
   id: string | number;
+
+  /**
+   * Whether this module was in method shorthand format
+   */
+  isShorthand?: boolean;
 }
 
 /**

webpack/webpack5-module-minifier-plugin/src/RehydrateAsset.ts

@@ -46,7 +46,8 @@ export function rehydrateAsset(
   // RegExp.exec uses null or an array as the return type, explicitly
   let match: RegExpExecArray | null = null;
   while ((match = CHUNK_MODULE_REGEX.exec(assetCode))) {
-    const hash: string = match[1];
+    const leadingColon: string = match[1]; // Captured ':' or empty string
+    const hash: string = match[2]; // The module hash
 
     const moduleSource: IModuleInfo | undefined = moduleMap.get(hash);
     if (moduleSource === undefined) {
@@ -66,6 +67,15 @@ export function rehydrateAsset(
     lastStart = CHUNK_MODULE_REGEX.lastIndex;
 
     if (moduleSource) {
+      // Check if this module was in shorthand format
+      const isShorthand: boolean = moduleSource.isShorthand === true;
+
+      // For shorthand format, omit the colon. For regular format, keep it.
+      if (!isShorthand && leadingColon) {
+        source.add(leadingColon);
+        charOffset += leadingColon.length;
+      }
+
       const charLength: number = moduleSource.source.source().length;
 
       if (emitRenderInfo) {
@@ -78,6 +88,12 @@ export function rehydrateAsset(
       source.add(moduleSource.source);
       charOffset += charLength;
     } else {
+      // Keep the colon if present for error module
+      if (leadingColon) {
+        source.add(leadingColon);
+        charOffset += leadingColon.length;
+      }
+
       const errorModule: string = `()=>{throw new Error(\`Missing module with hash "${hash}"\`)}`;
 
       source.add(errorModule);

webpack/webpack5-module-minifier-plugin/src/index.ts

@@ -4,6 +4,8 @@
 export {
   MODULE_WRAPPER_PREFIX,
   MODULE_WRAPPER_SUFFIX,
+  MODULE_WRAPPER_SHORTHAND_PREFIX,
+  MODULE_WRAPPER_SHORTHAND_SUFFIX,
   CHUNK_MODULE_TOKEN,
   CHUNK_MODULE_REGEX,
   STAGE_BEFORE,

webpack/webpack5-module-minifier-plugin/src/test/MockMinifier.ts

@@ -8,7 +8,12 @@ import type {
   IMinifierConnection
 } from '@rushstack/module-minifier';
 
-import { MODULE_WRAPPER_PREFIX, MODULE_WRAPPER_SUFFIX } from '../Constants';
+import {
+  MODULE_WRAPPER_PREFIX,
+  MODULE_WRAPPER_SUFFIX,
+  MODULE_WRAPPER_SHORTHAND_PREFIX,
+  MODULE_WRAPPER_SHORTHAND_SUFFIX
+} from '../Constants';
 
 export class MockMinifier implements IModuleMinifier {
   public readonly requests: Map<string, string> = new Map();
@@ -24,12 +29,27 @@ export class MockMinifier implements IModuleMinifier {
     this.requests.set(hash, code);
 
     const isModule: boolean = code.startsWith(MODULE_WRAPPER_PREFIX);
-    const processedCode: string = isModule
-      ? `${MODULE_WRAPPER_PREFIX}\n// Begin Module Hash=${hash}\n${code.slice(
-          MODULE_WRAPPER_PREFIX.length,
-          -MODULE_WRAPPER_SUFFIX.length
-        )}\n// End Module${MODULE_WRAPPER_SUFFIX}`
-      : `// Begin Asset Hash=${hash}\n${code}\n// End Asset`;
+    const isShorthandModule: boolean = code.startsWith(MODULE_WRAPPER_SHORTHAND_PREFIX);
+
+    let processedCode: string;
+    if (isShorthandModule) {
+      // Handle shorthand format
+      // Add comment markers similar to regular format
+      const innerCode: string = code.slice(
+        MODULE_WRAPPER_SHORTHAND_PREFIX.length,
+        -MODULE_WRAPPER_SHORTHAND_SUFFIX.length
+      );
+      processedCode = `${MODULE_WRAPPER_SHORTHAND_PREFIX}\n// Begin Module Hash=${hash}\n${innerCode}\n// End Module\n${MODULE_WRAPPER_SHORTHAND_SUFFIX}`;
+    } else if (isModule) {
+      // Handle regular format
+      processedCode = `${MODULE_WRAPPER_PREFIX}\n// Begin Module Hash=${hash}\n${code.slice(
+        MODULE_WRAPPER_PREFIX.length,
+        -MODULE_WRAPPER_SUFFIX.length
+      )}\n// End Module${MODULE_WRAPPER_SUFFIX}`;
+    } else {
+      // Handle asset format
+      processedCode = `// Begin Asset Hash=${hash}\n${code}\n// End Asset`;
+    }
 
     callback({
       hash,