refractor filename modify logic

Author: lcxfs1991

README.md

@@ -68,7 +68,7 @@ new ExtractTextPlugin(options: filename | object)
 |Name|Type|Description|
 |:--:|:--:|:----------|
 |**`id`**|`{String}`|Unique ident for this plugin instance. (For advanced usage only, by default automatically generated)|
-|**`filename`**|`{String|Object}`|Name of the result file. May contain `[name]`, `[id]` and `[contenthash]`|
+|**`filename`**|`{String|Function}`|Name of the result file. May contain `[name]`, `[id]` and `[contenthash]`|
 |**`allChunks`**|`{Boolean}`|Extract from all additional chunks too (by default it extracts only from the initial chunk(s))|
 |**`disable`**|`{Boolean}`|Disables the plugin|
 |**`ignoreOrder`**|`{Boolean}`|Disables order check (useful for CSS Modules!), `false` by default|
@@ -157,21 +157,17 @@ module.exports = {
 
 ### Modify filename
 
-`filename` parameter could be `Object`. It accepts `format` and `modify` callback as attributes.
-In the following config, before `modify` callback is called, the css path would be `css/js/a.css`.
-After `modify` callback, it is transformed to `css/a.css`.
+`filename` parameter could be `Function`. It passes `getPath` to process the format like `css/[name].css` and returns the real file name, `css/js/a.css`. You can replace `css/js` with `css` then you will get the new path `css/a.css`.
+
 
 ```js
 entry: {
   'js/a': "./a"
 },
 plugins: [
   new ExtractTextPlugin({
-    filename:  {
-      format: 'css/[name].css',
-      modify: (filename) => {
-        return filename.replace('css/js', 'css');
-      }
+    filename:  (getPath) => {
+      return getPath('css/[name].css').replace('css/js', 'css');
     },
     allChunks: true
   })

index.js

@@ -329,23 +329,15 @@ ExtractTextPlugin.prototype.apply = function(compiler) {
 					});
 					var chunk = extractedChunk.originalChunk;
 					var source = this.renderExtractedChunk(extractedChunk);
-					
-					var format = filename;
-
-					if (isObject(filename)) {
-						format = filename.format;
-					}
 
-					var file = compilation.getPath(format, {
+					var getPath = (format) => compilation.getPath(format, {
 						chunk: chunk
 					}).replace(/\[(?:(\w+):)?contenthash(?::([a-z]+\d*))?(?::(\d+))?\]/ig, function() {
 						return loaderUtils.getHashDigest(source.source(), arguments[1], arguments[2], parseInt(arguments[3], 10));
 					});
-					
-					if (isFunction(filename.modify)) {
-						file = filename.modify(file);
-					}
 
+					var file = (isFunction(filename)) ? filename(getPath) : getPath(filename);
+					
 					compilation.assets[file] = source;
 					chunk.files.push(file);
 				}

schema/plugin-schema.json

@@ -23,7 +23,7 @@
       "description": "The filename and path that ExtractTextPlugin will extract to",
       "modes": {
         "type": "string",
-        "type": "object"
+        "type": "function"
       }
     },
     "ignoreOrder": {

test/cases/multiple-entries-filename/expected/a.txt

@@ -0,0 +1,2 @@
+a
+b

test/cases/multiple-entries-filename/expected/b.txt

@@ -0,0 +1,2 @@
+a
+c

test/cases/multiple-entries-filename/webpack.config.js

@@ -6,13 +6,10 @@ module.exports = {
 	},
 	plugins: [
 		new ExtractTextPlugin({
-			filename:  {
-				format: 'txt/[name].txt',
-				modify: (filename) => {
-					return filename.replace('txt/js', 'txt');
-				}
+			filename:  (getPath) => {
+				return getPath('txt/[name].txt').replace('txt/js', '');
 			},
 			allChunks: true
 		})
 	]
-};
+};