React native change listening port

Question

I am using react native android and having face issues to deploy the app on an android device. When I run

react-native start, it won't start dev server on port 8081

I have tried a few options mentioned at:

1. https://facebook.github.io/react-native/docs/troubleshooting.html

2. Tried to stop the process running at port number 8081, but no success

My question is that can we change the React Native dev server port from 8081 (which is a default in android however the same we can change in ios from AppDelegate.m file) to something else or any other approach

Your responses will be highly appreciated. Thanks

Answer 1

Not sure if this is documented or not[1], you can specify the port via a CLI argument, like this:

react-native start --port 9988 

I found it in the source code, and it worked on my local machine :)

https://github.com/facebook/react-native/blob/master/local-cli/server/server.js#L30

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[1] This is now documented here: https://facebook.github.io/react-native/docs/troubleshooting#using-a-port-other-than-8081

Answer 2

I know it is late but FYI, there is also another way where you can change your port permanently.

Go to your_app\node_modules\react-native\local-cli\server\server.js and change the port 8081 to 8088

which will be something like this

    ...       module.exports = {       name: 'start',       func: server,       description: 'starts the webserver',       options: [{         command: '--port [number]',         default: 8088,         parse: (val) => Number(val),       }      ... 

UPDATE TESTED ON RN 0.57:
1. If you are using custom metro config

const config = {   ...   server: {     port: 8088,   }   ... }; 

2. And if you are not then,
Go to your_app\node_modules\react-native\local-cli\util\Config.js

const Config = {    ...    server: {       port: process.env.RCT_METRO_PORT || 8088 //changed from 8081    }    ... }