How to change the default port in react js

Question

I could able to start react js with default port 3000. But, when I customised the port to 4200, "start": "PORT=4200 react-scripts start"(Just changed in the package.json), I am not able to start the react js application.

'PORT' is not recognized as an internal or external command,
operable program or batch file.
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! todo-app@0.1.0 start: `PORT=4200 react-scripts start`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the todo-app@0.1.0 start script.
npm ERR! This is probably not a problem with npm. There is likely additional lo
ging output above.

npm ERR! A complete log of this run can be found in:

I guess you're using Windows - that syntax is how to set an env var in *nix. — jonrsharpe, Jun 25 '19 at 16:27

score 16 · Answer 1 · answered Jun 25 '19 at 16:30

16

to start APP on another port run the following npm command

npm start --port 3002

or to config in package use

replace the start command with below

"start": "set PORT=3006 && react-scripts start"

answered Jun 25 '19 at 16:30

Manrah

491
3
13

@ Manpreet Its worked !! Thank you . – java learning Jun 25 '19 at 16:39
@javalearning . welcome – Manrah Jun 26 '19 at 06:07
It worked for me – Jorge Santos Neill Nov 12 '19 at 16:14
Thanks, It worked for me also specially & – Krishan Kumar Dec 08 '21 at 11:21

score 10 · Answer 2 · answered Jun 25 '19 at 18:00

10

An other option that was not mentioned in the other answer would be to create a .env file in the root directory and put PORT=4200 in it. It will automatically be loaded in your environment variables.

answered Jun 25 '19 at 18:00

Antoine Gagnon

611
4
13

How to change the default port in react js

2 Answers2