How to modify the default port number 3000 for a project created with create react app

Jintian 2020-11-12 23:20:08
modify default port number project


solve

It's simple , You can set environment variables before starting PORT, This application will read the parameters in the environment variables at startup , If not, use the default 3000( Port number ).

Set the environment variable , It is more convenient to modify directly packcage.json in scripts Medium start Option value .
Before the change :"start": "react-scripts start",
After modification :"start": "set PORT=8080 && react-scripts start",

In addition, you can also use the normal environment variable setting method .

Start again , The app will use the settings you just set .

principle

Use create-react-app After creating the project framework ,packcage.json There are the following 4 Basic orders :

"scripts": {

"start": "set PORT=8080 && react-scripts start",
"build": "react-scripts build",
"test": "react-scripts test",
"eject": "react-scripts eject"
},

When the dependency is installed npm install after , perform npm run <script_name>, The corresponding execution command of the script will be called .
Such as :npm run build Will be in scripts Look for the script name in build, The corresponding command is react-scripts build, Then perform .
react-scripts It is actually a dependency that has been installed in this project . Can be in node_modules Find the corresponding download directory in the directory .
 Insert picture description here
so : In the current project ./node_modules/react_scripts/scripts/ There are several script files in the directory .
And we are package.json The script commands configured in respectively execute several script files here .

./node_modules/react_scripts/scripts/start.js There are two lines of code in :

const DEFAULT_PORT = parseInt(process.env.PORT, 10) || 3000;
const HOST = process.env.HOST || '0.0.0.0';

Or modify it directly Local downloaded dependency Default configuration in , Such as the slogan 3000( It's highly discouraged ).
or , Through environment variables PORT Pass in the port number to the program .

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