可以在plugin加入參數即可，v4跟v2版本有很大的差異。

在此提供兩種版本的方式。

Webpack v4

// 需引入uglifyjs-webpack-plugin,這邊與v2就不一樣
const UglifyJsPlugin = require('uglifyjs-webpack-plugin');
plugins: [
    new UglifyJsPlugin({
        sourceMap: true,
        uglifyOptions: {
            ie8: false,
            ecma: 8,
            parse: {},
            mangle: true,
            output: {
                comments: false,
                beautify: false
            },
            compress: true,
            warnings: false
            }
    })
]

Webpack v2

// v2 版本直接使用webpack.optimize即可
plugins: [
    new webpack.optimize.UglifyJsPlugin({
        sourceMap: true,
        compress: {
            warnings: false, // remove 警告
            drop_console: true // 移除console.log
        }
    })
]

Reference

https://blog.csdn.net/xiaoguang44/article/details/89555376

https://blog.csdn.net/xiasohuai/article/details/88527483

https://segmentfault.com/a/1190000015032321

DeprecationWarning: Chunk.modules is deprecated. Use Chunk.getNumberOfModules/mapModules/forEachModule/containsModule instead.

查詢要更新哪個套件，更新node_module後即可，

$ npm install extract-text-webpack-plugin@3

npm 上面也已經提示不推薦使用，沒有在維護了！

extract-text-webpack-plugin

“建議改使用”

mini-css-extract-plugin

Reference

https://github.com/webpack-contrib/extract-text-webpack-plugin/issues/529

(node:36968) DeprecationWarning: loaderUtils.parseQuery() received a non-string value which can be problematic, see https://github.com/webpack/loader-utils/issues/56
parseQuery() will be replaced with getOptions() in the next major version of loader-utils.

並非webpack prod錯誤，而是套件太舊，查一下package.json以為是loader.utils.

結果node_module沒有這套件上查了，是babel-loader這套件。

跳出這錯誤是我用6.x.x版本，直接升級上去會到8.x.x版本，又會跳出babel-core的問題，

所以我改成指定 7.x.x版本

$ npm install babel-loader@7

Reference

https://github.com/babel/babel-loader/issues/392

You are currently using minified code outside of NODE_ENV === ‘production’. This means that you are running a slower development build of Redux. You can use loose-envify (https://github.com/zertosh/loose-envify) for browserify or DefinePlugin for webpack (http://stackoverflow.com/questions/30030031) to ensure you have the correct code for your production build.

找了很多文章，都是說在webpack.config.js加上此句，

new webpack.DefinePlugin({
            'process.env': {
                NODE_ENV: JSON.stringify('development')
            }
        })

或是將react-router從v3升級v4，但我原本就使用4.0.0了，但還是嘗試升級看看，

反而我從4.0.0升到4.0.5又出現其他錯誤訊息，只好將回4.0.0版本，

不管怎麼在設定檔案上做NODE_ENV的參數，都會報錯，

後來看到此command設定：

"dev": "webpack --mode development",

    "build": "webpack --mode production"

好像可以解決我的問題，但我又發現我是使用webpack-dev-middleware，

並沒有地方可以設定command，幸好在原本的webpack.config.js可以加上此參數

mode:”development”

module.exports = {
    mode:"development",
    //入口文件
    entry:{
        'webpack-hot-middleware/client',
        path.resolve(__dirname, 'react')
    },
...
...

設定完後，重新啟動start:dev，就沒有在跑出此錯誤訊息了！

mode此參數為v4所新增的。

Reference

https://blog.csdn.net/jiang7701037/article/details/80682662