Improve assets warning, remove unnecessary pattern matching in option

Author: NekR

lib/index.js

@@ -306,15 +306,11 @@ var OfflinePlugin = (function () {
               var index = assets.indexOf(cacheKey);
 
               externalsCheck: if (index === -1) {
-                if (_this3.externals.some(function (glob) {
-                  if ((0, _minimatch2['default'])(cacheKey, glob)) {
-                    return true;
-                  }
-                })) {
+                if (_this3.externals.length && _this3.externals.indexOf(cacheKey) !== -1) {
                   break externalsCheck;
                 }
 
-                compilation.warnings.push(new Error('OfflinePlugin: Cache asset [' + cacheKey + '] is not found in output assets'));
+                compilation.warnings.push(new Error('OfflinePlugin: Cache asset [' + cacheKey + '] is not found in output assets,' + 'if it\'s an external asset, put it to |externals| option to remove this warning'));
               } else {
                 assets.splice(index, 1);
               }

src/index.js

@@ -318,16 +318,15 @@ export default class OfflinePlugin {
           const index = assets.indexOf(cacheKey);
 
           externalsCheck: if (index === -1) {
-            if (this.externals.some((glob) => {
-              if (minimatch(cacheKey, glob)) {
-                return true;
-              }
-            })) {
+            if (this.externals.length && this.externals.indexOf(cacheKey) !== -1) {
               break externalsCheck;
             }
 
             compilation.warnings.push(
-              new Error(`OfflinePlugin: Cache asset [${ cacheKey }] is not found in output assets`)
+              new Error(
+                `OfflinePlugin: Cache asset [${ cacheKey }] is not found in output assets,` +
+                `if it's an external asset, put it to |externals| option to remove this warning`
+              )
             );
           } else {
             assets.splice(index, 1);