How to solve the Error in deploying react app on Heroku - node.js

Question

I run yarn install and yarn start locally for my project and it works fine. However, as soon as I push it to Heroku, I am unable to deploy it with the following error log:
2021-05-10T16:40:06.622555+00:00 app[web.1]: > react-scripts start
2021-05-10T16:40:06.622556+00:00 app[web.1]:
2021-05-10T16:40:06.627252+00:00 app[web.1]: sh: 1: react-scripts: not found
2021-05-10T16:40:06.636894+00:00 app[web.1]: npm ERR! code ELIFECYCLE
2021-05-10T16:40:06.637303+00:00 app[web.1]: npm ERR! syscall spawn
2021-05-10T16:40:06.637496+00:00 app[web.1]: npm ERR! file sh
2021-05-10T16:40:06.637766+00:00 app[web.1]: npm ERR! errno ENOENT
2021-05-10T16:40:06.644457+00:00 app[web.1]: npm ERR! bleh#0.1.0 start: `react-scripts start`
2021-05-10T16:40:06.644627+00:00 app[web.1]: npm ERR! spawn ENOENT
2021-05-10T16:40:06.644771+00:00 app[web.1]: npm ERR!
2021-05-10T16:40:06.644922+00:00 app[web.1]: npm ERR! Failed at the bleh#0.1.0 start script.
2021-05-10T16:40:06.645043+00:00 app[web.1]: npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
2021-05-10T16:40:06.654910+00:00 app[web.1]:
2021-05-10T16:40:06.655128+00:00 app[web.1]: npm ERR! A complete log of this run can be found in:
2021-05-10T16:40:06.655306+00:00 app[web.1]: npm ERR! /app/.npm/_logs/2021-05-10T16_40_06_646Z-debug.log
2021-05-10T16:40:06.706089+00:00 heroku[web.1]: Process exited with status 1
2021-05-10T16:40:06.778374+00:00 heroku[web.1]: State changed from starting to crashed
2021-05-10T16:41:26.103511+00:00 app[api]: Deploy 1f4ec645 by user holliu9999#gmail.com
2021-05-10T16:41:26.103511+00:00 app[api]: Release v7 created by user holliu9999#gmail.com
2021-05-10T16:41:26.390448+00:00 heroku[web.1]: State changed from crashed to starting
2021-05-10T16:41:30.000000+00:00 app[api]: Build succeeded
2021-05-10T16:41:32.398941+00:00 heroku[web.1]: Starting process with command `npm start`
In addition, I do only contain the yarn.lock in my directory so I am confused why it still runing npm. And here is my package.json file:
{
"name": "bleh",
"version": "0.1.0",
"private": true,
"devDependencies": {
"react-scripts": "0.9.0"
},
"dependencies": {
"react": "^15.4.2",
"react-dom": "^15.4.2",
"react-fontawesome": "^1.6.1",
"react-infinite": "^0.11.2",
"react-infinite-loader": "^1.0.2",
"react-router": "^3.0.2"
},
"scripts": {
"start": "react-scripts start",
"build": "react-scripts build",
"test": "react-scripts test --env=jsdom",
"eject": "react-scripts eject"
}
}

Answer 1

You need to have a back-end server like node with express and config the script npm start. Go to Package.json --> scripts --> and add the script --> "start": "node app or index" depend of your root file. Btw you need to put the react application on the public folder of your backend.
Heroku needs a backend to start correctly.
You can see the express setup https://www.npmjs.com/package/express or http://expressjs.com/en/starter/hello-world.html