Solve the error that npm run dev reports that 'webpack-dev-server' is not an internal command or an external command

Error image

The reason for the error is that you did not install some dependencies

Solution One

first step

npm install --registry=https://registry.npm.taobao.org

When installing, it is best to get the Taobao image into it faster registry = https: //registry.npm.taobao.org

There may be an error in this part: please see solution two

Second step

npm run build 

third step

npm run dev

Successfully resolved

Solution two

npm install error

D:\vue-playlist>npm install

> uglifyjs-webpack-plugin@0.4.6 postinstall D:\vue-playlist\node_modules\webpack\node_modules\uglifyjs-webpack-plugin
> node lib/post_install.js

npm WARN ajv-keywords@3.2.0 requires a peer of ajv@^6.0.0 but none is installed. You must install peer dependencies yourself.
npm WARN The package vue-router is included as both a dev and production dependency.
npm WARN optional SKIPPING OPTIONAL DEPENDENCY: fsevents@1.2.4 (node_modules\fsevents):
npm WARN notsup SKIPPING OPTIONAL DEPENDENCY: Unsupported platform for fsevents@1.2.4: wanted {"os":"darwin","arch":"any"} (current: {"os":"win32","arch":"x64"})

added 865 packages from 478 contributors, updated 28 packages and audited 10653 packages in 160.56s
found 2 vulnerabilities (1 moderate, 1 high)
 run `npm audit fix` to fix them, or `npm audit` for details

Execute the following command

npm audit fix --force

Successfully resolved