feat: do not hash localName if the localName is inlined:

Adds a new setting .modules.hashStrategy, default is backward-compat
webpack-contrib · Jan 26, 2022 · 8e93b75 · 8e93b75
1 parent cbe3898
commit 8e93b75
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Showing 6 changed files with 910 additions and 17 deletions.
diff --git a/README.md b/README.md
@@ -872,6 +872,37 @@ module.exports = {
 };
 ```
 
+##### `hashStrategy`
+
+Type: `'use-local-name' | 'omit-local-name' | 'auto'`
+Default: `'use-local-name'`
+
+Should local name be used when computing the hash.
+
+- `'auto'` Auto detect based on [localIdentName](#localidentname). Use this value to get the output that is better compressable by GZIP or Brotli.
+- `'use-local-name'` Each identifier in a module gets its own hash digest.
+- `'omit-local-name'` All identifiers from the same module shares the same hash digest. Handle with care!
+
+**webpack.config.js**
+
+```js
+module.exports = {
+  module: {
+    rules: [
+      {
+        test: /\.css$/i,
+        loader: "css-loader",
+        options: {
+          modules: {
+            hashStrategy: "auto",
+          },
+        },
+      },
+    ],
+  },
+};
+```
+
 ##### `localIdentRegExp`
 
 Type: `String|RegExp`

diff --git a/src/options.json b/src/options.json
@@ -114,6 +114,11 @@
               "link": "https://github.com/webpack-contrib/css-loader#localidenthashdigestlength",
               "type": "number"
             },
+            "hashStrategy": {
+              "description": "Allows to specify should localName be used when computing the hash.",
+              "link": "https://github.com/webpack-contrib/css-loader#hashstrategy",
+              "enum": ["use-local-name", "omit-local-name", "auto"]
+            },
             "localIdentRegExp": {
               "description": "Allows to specify custom RegExp for local ident name.",
               "link": "https://github.com/webpack-contrib/css-loader#localidentregexp",

diff --git a/src/utils.js b/src/utils.js
@@ -330,14 +330,28 @@ function defaultGetLocalIdent(
   localName,
   options
 ) {
-  const { context, hashSalt } = options;
+  const { context, hashSalt, hashStrategy } = options;
   const { resourcePath } = loaderContext;
   const relativeResourcePath = normalizePath(
     path.relative(context, resourcePath)
   );
 
+  let useLocalNameInHash;
+  switch (hashStrategy) {
+    case "omit-local-name":
+      useLocalNameInHash = false;
+      break;
+    case "auto":
+      useLocalNameInHash = !/\[local\]/.test(localIdentName);
+      break;
+    default:
+      // undefined or "use-local-name"
+      useLocalNameInHash = true;
+  }
   // eslint-disable-next-line no-param-reassign
-  options.content = `${relativeResourcePath}\x00${localName}`;
+  options.content = useLocalNameInHash
+    ? `${relativeResourcePath}\x00${localName}`
+    : relativeResourcePath;
 
   let { hashFunction, hashDigest, hashDigestLength } = options;
   const matches = localIdentName.match(
@@ -756,6 +770,7 @@ function getModulesPlugins(options, loaderContext) {
     localIdentHashDigest,
     localIdentHashDigestLength,
     localIdentRegExp,
+    hashStrategy,
   } = options.modules;
 
   let plugins = [];
@@ -780,6 +795,7 @@ function getModulesPlugins(options, loaderContext) {
                 hashFunction: localIdentHashFunction,
                 hashDigest: localIdentHashDigest,
                 hashDigestLength: localIdentHashDigestLength,
+                hashStrategy,
                 regExp: localIdentRegExp,
               }
             );
@@ -798,6 +814,7 @@ function getModulesPlugins(options, loaderContext) {
                 hashFunction: localIdentHashFunction,
                 hashDigest: localIdentHashDigest,
                 hashDigestLength: localIdentHashDigestLength,
+                hashStrategy,
                 regExp: localIdentRegExp,
               }
             );