refractor filename modify logic

.gitignore

@@ -6,3 +6,5 @@
 /coverage
 
 /.idea
+
+.DS_Store

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}`|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|
@@ -155,6 +155,25 @@ module.exports = {
 }
 ```
 
+### Modify filename
+
+`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:  (getPath) => {
+      return getPath('css/[name].css').replace('css/js', 'css');
+    },
+    allChunks: true
+  })
+]
+```
+
 <h2 align="center">Maintainer</h2>
 
 <table>

index.js

@@ -152,6 +152,14 @@ function isString(a) {
 	return typeof a === "string";
 }
 
+function isFunction(a) {
+	return isType('Function', a);
+}
+
+function isType(type, obj) {
+	return Object.prototype.toString.call(obj) === '[object ' + type + ']';
+}
+
 ExtractTextPlugin.loader = function(options) {
 	return { loader: require.resolve("./loader"), options: options };
 };
@@ -317,11 +325,15 @@ ExtractTextPlugin.prototype.apply = function(compiler) {
 					});
 					var chunk = extractedChunk.originalChunk;
 					var source = this.renderExtractedChunk(extractedChunk);
-					var file = compilation.getPath(filename, {
+
+					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));
 					});
+
+					var file = (isFunction(filename)) ? filename(getPath) : getPath(filename);
+
 					compilation.assets[file] = source;
 					chunk.files.push(file);
 				}

schema/plugin-schema.json

@@ -21,7 +21,10 @@
     },
     "filename": {
       "description": "The filename and path that ExtractTextPlugin will extract to",
-      "type": "string"
+      "modes": {
+        "type": "string",
+        "type": "function"
+      }
     },
     "ignoreOrder": {
       "description": "Ignore dependency order (useful for CSS Modules)",

test/cases/multiple-entries-filename/a.js

@@ -0,0 +1,4 @@
+require.ensure([], function() {
+	require("./a.txt");
+	require("./b.txt");
+});

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

@@ -0,0 +1 @@
+a

test/cases/multiple-entries-filename/b.js

@@ -0,0 +1,4 @@
+require.ensure([], function() {
+	require("./a.txt");
+	require("./c.txt");
+});

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

@@ -0,0 +1 @@
+b

test/cases/multiple-entries-filename/c.txt

@@ -0,0 +1 @@
+c

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/expected/txt/a.txt

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

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

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

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

@@ -0,0 +1,15 @@
+var ExtractTextPlugin = require("../../../");
+module.exports = {
+	entry: {
+		'js/a': "./a",
+		'js/b': "./b"
+	},
+	plugins: [
+		new ExtractTextPlugin({
+			filename:  (getPath) => {
+				return getPath('txt/[name].txt').replace('txt/js', '');
+			},
+			allChunks: true
+		})
+	]
+};