Reactjs 在react中undo撤消'npm run eject'

I was trying to test the performance of my React app(created with create-react-app) with react CDN script and i did 'npm run eject' to add webpack externals dependencies react and react-dom.

I did that with ease in webpack config and <script> in index.html

...
externals: {
    react: 'React',
    'react-dom':'ReactDOM'
},
...

Now I want to revert it back to previous state

我跑了git checkout master和npm start

> myapp@0.18.1 start /home/code/serverSync/myapp/ui
> react-scripts start

sh: 1: react-scripts: not found

npm ERR! Linux 4.15.0-23-generic
npm ERR! argv "/usr/bin/node" "/usr/bin/npm" "start"
npm ERR! node v8.10.0
npm ERR! npm  v3.5.2
npm ERR! file sh
npm ERR! code ELIFECYCLE
npm ERR! errno ENOENT
npm ERR! syscall spawn
npm ERR! myapp@0.18.1 start: `react-scripts start`
npm ERR! spawn ENOENT
npm ERR! 
npm ERR! Failed at the myapp@0.18.1 start script 'react-scripts start'.
npm ERR! Make sure you have the latest version of node.js and npm installed.
npm ERR! If you do, this is most likely a problem with the myapp package,
npm ERR! not with npm itself.
npm ERR! Tell the author that this fails on your system:
npm ERR!     react-scripts start
npm ERR! You can get information on how to open an issue for this project with:
npm ERR!     npm bugs myapp
npm ERR! Or if that isn't available, you can get their info via:
npm ERR!     npm owner ls myapp
npm ERR! There is likely additional logging output above.

npm ERR! Please include the following file with any support request:
npm ERR!     /home/code/serverSync/myapp/ui/npm-debug.log

我怎样才能回到主分行？