VSCode拡張でpackage.jsonの変更を検知して自動的にnpm installされてください

npm install -g yo generator-code

yo code

     _-----_     ╭──────────────────────────╮
    |       |    │   Welcome to the Visual  │
    |--(o)--|    │   Studio Code Extension  │
   `---------´   │        generator!        │
    ( _´U`_ )    ╰──────────────────────────╯
    /___A___\   /
     |  ~  |
   __'.___.'__
 ´   `  |° ´ Y `

? What type of extension do you want to create? New Extension (TypeScript)
? What's the name of your extension? watch-package-json
? What's the identifier of your extension? watch-package-json
? What's the description of your extension? watch your local package.json and do npm i.
? Initialize a git repository? Yes
? Bundle the source code with webpack? Yes
? Which package manager to use? npm

asazutaiga.watch-package-json