Node.js Child Processes Explained #shorts

Child processes in Node.js allow us to execute external commands or scripts in our application. This can be useful for tasks such as running shell commands, executing scripts, or spawning new instances of Node.js processes. In this tutorial, we will explore how to use child processes in Node.js.

To work with child processes in Node.js, we will be using the built-in child_process module. This module provides several functions for creating and managing child processes.

To get started, let’s create a new Node.js application and install the child_process module by running the following command in your terminal:

npm install child_process

Next, let’s create a new JavaScript file (e.g., childProcessExample.js) and require the child_process module at the top of the file:

const { spawn } = require('child_process');

Now, we can use the spawn function to create a new child process. The spawn function takes the command to execute as the first argument and an array of arguments as the second argument. For example, let’s spawn a new ls process (list files in the current directory):

const ls = spawn('ls', ['-lh', '/usr']);

In this example, we are spawning a new ls process and passing the -lh flag and the /usr directory as arguments.

Next, we can listen for events on the child process, such as stdout (standard output) and stderr (standard error). For example, we can log the output of the process to the console:

ls.stdout.on('data', (data) => {
  console.log(`stdout: ${data}`);
});

ls.stderr.on('data', (data) => {
  console.error(`stderr: ${data}`);
});

ls.on('close', (code) => {
  console.log(`child process exited with code ${code}`);
});

In this code snippet, we are listening for the data event on the stdout and stderr streams of the child process. When data is received, we log it to the console. Additionally, we listen for the close event to know when the child process has exited and log its exit code.

Finally, to run the child process, we need to execute the JavaScript file in Node.js:

node childProcessExample.js

This will spawn a new ls process and print the output to the console.

In conclusion, using child processes in Node.js allows us to execute external commands or scripts in our application. The child_process module provides functions such as spawn to create and manage child processes. By listening for events on the child process, we can handle the output and exit codes of the process. I hope this tutorial was helpful in understanding how to work with child processes in Node.js. Happy coding!