added an option to specify 'only' as a selector for files to purge

Author: somebody32

lib/purgecss-webpack-plugin.es.js

@@ -166,13 +166,20 @@ var PurgecssPlugin = function () {
         });
 
         compilation.plugin('additional-assets', function (cb) {
+          var assetsFromCompilation = assets(compilation.assets, ['.css']);
           // Go through chunks and purge as configured
           compilation.chunks.forEach(function (chunk) {
             var chunkName = chunk.name,
                 files$$1 = chunk.files;
 
-            var assetsToPurge = assets(compilation.assets, ['.css']).filter(function (asset) {
-              return files$$1.indexOf(asset.name) >= 0;
+            var assetsToPurge = assetsFromCompilation.filter(function (asset) {
+              if (_this.options.only) {
+                return [].concat(_this.options.only).some(function (only) {
+                  return asset.name.indexOf(only) >= 0;
+                });
+              } else {
+                return files$$1.indexOf(asset.name) >= 0;
+              }
             });
 
             assetsToPurge.forEach(function (_ref) {

lib/purgecss-webpack-plugin.js

@@ -170,13 +170,20 @@ var PurgecssPlugin = function () {
         });
 
         compilation.plugin('additional-assets', function (cb) {
+          var assetsFromCompilation = assets(compilation.assets, ['.css']);
           // Go through chunks and purge as configured
           compilation.chunks.forEach(function (chunk) {
             var chunkName = chunk.name,
                 files$$1 = chunk.files;
 
-            var assetsToPurge = assets(compilation.assets, ['.css']).filter(function (asset) {
-              return files$$1.indexOf(asset.name) >= 0;
+            var assetsToPurge = assetsFromCompilation.filter(function (asset) {
+              if (_this.options.only) {
+                return [].concat(_this.options.only).some(function (only) {
+                  return asset.name.indexOf(only) >= 0;
+                });
+              } else {
+                return files$$1.indexOf(asset.name) >= 0;
+              }
             });
 
             assetsToPurge.forEach(function (_ref) {

src/index.js

@@ -18,12 +18,21 @@ export default class PurgecssPlugin {
       })
 
       compilation.plugin('additional-assets', cb => {
+        const assetsFromCompilation = search.assets(compilation.assets, [
+          '.css'
+        ])
         // Go through chunks and purge as configured
         compilation.chunks.forEach(chunk => {
           const { name: chunkName, files } = chunk
-          const assetsToPurge = search
-            .assets(compilation.assets, ['.css'])
-            .filter(asset => files.indexOf(asset.name) >= 0)
+          const assetsToPurge = assetsFromCompilation.filter(asset => {
+            if (this.options.only) {
+              return []
+                .concat(this.options.only)
+                .some(only => asset.name.indexOf(only) >= 0)
+            } else {
+              return files.indexOf(asset.name) >= 0
+            }
+          })
 
           assetsToPurge.forEach(({ name, asset }) => {
             const filesToSearch = parse