$ npm run serve

> yunkeanxin_1_front2@0.1.0 serve
> vue-cli-service serve

sh: 1: vue-cli-service: not found

$ npm install

$ yarn install 

$ npm run serve

> yunkeanxin_1_front2@0.1.0 serve
> vue-cli-service serve

 INFO  Starting development server...

 DONE  Compiled successfully in 5584ms                                                                                                                                                                   2:23:32 PM

  App running at:
  - Local:   http://localhost:8080/ 
  - Network: http://192.168.10.4:8080/

  Note that the development build is not optimized.
  To create a production build, run npm run build.