How to modify the port of nodejs

Node.js is a JavaScript running environment based on the Chrome V8 engine. It is a server-side framework with a non-blocking I/O model. In Node.js, we can create an HTTP server by listening to the specified port. Commonly used port numbers include 80, 443, 3000, etc. But sometimes we need to change the port number of Node.js to meet specific needs. This article will introduce how to modify the Node.js port number.

1. Using command line parameters

When using Node.js to create an HTTP server, you can specify the port number through command line parameters. The specific operation method is as follows:

Run the following command in the terminal:

node app.js 8080

Among them, app.js is your Node.js code file, and 8080 is the port number you want to listen to.

There is a global object process in Node.js, which contains relevant information available in the Node.js process and methods to control the node process. Through the process object, we can get the command line parameters.

Open the app.js file and add the following line of code:

const port = process.argv[2] || 3000;

app.listen(port, () => {
  console.log(`Server listening on port ${port}`);
});

In the above code, we used process.argv to obtain the command line parameters and store them In variable port. If no command line parameters are passed in, 3000 is used by default as the port number. Finally, use the app.listen method to start the HTTP server.

With this method, we can directly specify the port number through the command line parameters, so that the port number of the Node.js server can be flexibly configured.

2. Using environment variables

In addition to using command line parameters, you can also use environment variables to specify the port number of the Node.js server.

In the terminal, you can set the environment variable through the following command:

export PORT=8080

Where, PORT is the name of the environment variable, and 8080 is the port number you want to monitor.

In Node.js code, you can get the port number by reading the environment variable. The specific operation method is as follows:

Open the app.js file and add the following code:

const port = process.env.PORT || 3000;

app.listen(port, () => {
  console.log(`Server listening on port ${port}`);
});

In the above code, we used process.env to obtain the environment variables, and Store it in the variable port. If the environment variable is not set, 3000 is used by default as the port number. Finally, use the app.listen method to start the HTTP server.

With this method, we can specify the server port number by setting environment variables when deploying Node.js applications.

Summary

There are two ways to modify the port number of Node.js: using command line parameters or using environment variables. Using command line parameters can directly specify the port number, which is more flexible; using environment variables is more suitable for deployment into a production environment. In general, according to different application scenarios, choose different methods to modify the port number of Node.js.

The above is the detailed content of How to modify the port of nodejs. For more information, please follow other related articles on the PHP Chinese website!