declare vue config explicitly (as the default), otherwise there will be a warning in console log

Author: wxiaoguang

webpack.config.js

@@ -196,6 +196,10 @@ export default {
     ],
   },
   plugins: [
+    new webpack.DefinePlugin({
+      __VUE_OPTIONS_API__: true, // at the moment, many Vue components still use the Vue Options API
+      __VUE_PROD_DEVTOOLS__: false, // do not enable devtools support in production
+    }),
     new VueLoaderPlugin(),
     new MiniCssExtractPlugin({
       filename: 'css/[name].css',