React.js, a powerful JavaScript library developed by Facebook, is used to build user interfaces, especially for single-page applications. You’ll often use it to build complex UIs out of small, reusable pieces called “components”. One question that arises often when dealing with React.js development is how to change the default host and port for the development server.
By default, React.js development server (often created using create-react-app) runs on localhost and on port 3000. However, there might be cases when you want to modify these settings, either because the port is being used by another application, or you want to bind the application to a different network interface.
Changing the Port in React.JS
Changing the port number for a React.js application is straightforward. Here is how you can do it.
Using .env file:
You can create a .env file in your root directory, where you can specify the port number. This file can be used to define any environment variables you want to use in your application. To change the port number, add the following line to the .env file.
PORT=8080
Replace “8080” with the desired port number.
Using package.json:
You can also change the port directly in the scripts section of the package.json file. For instance, if you are using react-scripts start to start your server, you can modify it as follows:
"scripts": {
"start": "PORT=8080 react-scripts start"
}
Replace “8080” with the desired port number. This method works on both Linux and macOS. However, if you are on Windows, you might need to use a package like cross-env to set environment variables:
"scripts": {
"start": "cross-env PORT=8080 react-scripts start"
}
Changing the Host in React.JS
Changing the host on which your React.js server runs can also be done with a bit of work. This process involves setting the HOST environment variable. This is particularly useful when you want to allow devices other than your development machine to access your application. Here’s how to do it:
Using .env file:
As with the port, you can set the HOST environment variable in the .env file in your root directory. Add the following line to the file:
HOST=0.0.0.0
Replace “0.0.0.0” with the hostname you want to use.
Via package.json:
Similarly, you can set the HOST environment variable in the scripts section of the package.json file. For example:
"scripts": {
"start": "HOST=0.0.0.0 react-scripts start"
}
Replace “0.0.0.0” with the hostname you want to use. For Windows users, remember to use cross-env:
"scripts": {
"start": "cross-env HOST=0.0.0.0 react-scripts start"
}
Recap
By manipulating environment variables, you can alter the default behavior of the React.js development server, customizing the host and port to your requirements. Using the .env file for these changes keeps your setup clean and centralized, and using the package.json file allows you to make script-specific adjustments.
However, when manipulating these settings, always remember to ensure that your chosen port number is not being used by another service and your chosen host name is correctly configured on your network. These factors can affect your application’s accessibility and performance.
Remember that changes to the .env file or the package.json file will require you to restart your development server if it is currently running. The new settings will take effect when you start your server again.
By learning how to modify these parameters, you gain more control over your development environment and can ensure that it aligns closely with your production environment or other specific needs.
