原因：這是新版webpack存在的BUG，卸載現有的新版本webpack，裝老版本就好
webpack-dev-server 版本需要從最新版本降低到如下版本,因為開始構建項目所用的插件版本太低
（1）、npm uninstall webpack-dev-server
（2）、npm install webpack-dev-server@2.9.1
（3）、npm run dev
===================
如何執行npm uninstall webpack-dev-server 也報錯的話只能用下面方法了
原因是你的node_modules有意外改動，導致依賴庫不完整。
解決：
1.刪除項目下的node_modules
2.在項目目錄下重新執行npm install 或者cnpm install，會重新生成node_modules
3.執行npm run build 或者cnpm run build
4.執行npm run dev 或者cnpm run dev
==================
PS E:\webcode\bigbullmobile> cnpm run dev
> bigbullmobile@1.0.0 dev E:\webcode\bigbullmobile
> webpack-dev-server --inline --progress --config build/webpack.dev.conf.js
internal/modules/cjs/loader.js:573
throw err;
^
Error: Cannot find module 'array-includes'
at Function.Module._resolveFilename (internal/modules/cjs/loader.js:571:15)
at Function.Module._load (internal/modules/cjs/loader.js:497:25)
at Module.require (internal/modules/cjs/loader.js:626:17)
at require (internal/modules/cjs/helpers.js:20:18)
at Object.<anonymous> (E:\webcode\bigbullmobile\node_modules\_webpack-dev-server@2.11.3@webpack-dev-server\lib\polyfills.js:6:18)
at Module._compile (internal/modules/cjs/loader.js:678:30)
at Object.Module._extensions..js (internal/modules/cjs/loader.js:689:10)
at Module.load (internal/modules/cjs/loader.js:589:32)
at tryModuleLoad (internal/modules/cjs/loader.js:528:12)
at Function.Module._load (internal/modules/cjs/loader.js:520:3)
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! bigbullmobile@1.0.0 dev: `webpack-dev-server --inline --progress --config build/webpack.dev.conf.js`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the bigbullmobile@1.0.0 dev script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
npm ERR! A complete log of this run can be found in:
npm ERR! C:\Users\zheng\AppData\Roaming\npm-cache\_logs\2019-01-26T18_31_50_813Z-debug.log
PS E:\webcode\bigbullmobile>