In Node.js, child processes provide a way to execute code in separate operating system processes. One common use case is to run code dynamically at runtime. In this blog post, we will explore how to implement run-time code evaluation in child processes in Node.js.

Prerequisites

Before we begin, make sure you have Node.js installed on your machine.

Creating a child process

To execute code in a child process, we need to create a new instance of the ChildProcess class from the child_process module. Here’s how you can create a child process in Node.js:

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

const child = spawn('node', ['-e', 'console.log("Child process code");']);

In the above example, we are creating a child process that runs a simple JavaScript code to log a message.

Sending code to the child process

Now that we have a child process, we can send code to be evaluated. We can use the stdin stream of the child process to send the code. Here’s an example:

const codeToEvaluate = 'console.log("Code evaluation result");';
child.stdin.write(codeToEvaluate);
child.stdin.end();

In the above example, we are sending a simple JavaScript code to the child process. The stdin.write() method is used to write the code to the stdin stream of the child process. Finally, we call stdin.end() to indicate that we have finished writing data.

Evaluating code in the child process

To evaluate the code in the child process, we need to listen for the data event on the stdout stream of the child process. Here’s an example:

child.stdout.on('data', (data) => {
  console.log(`Code evaluation result: ${data}`);
});

In the above example, we are listening for the data event and logging the result of code evaluation.

Conclusion

In this blog post, we learned how to implement run-time code evaluation in child processes in Node.js. We saw how to create a child process, send code to be evaluated, and receive the result of code evaluation. Leveraging child processes can be useful in scenarios where you need to run code dynamically at runtime.

With this knowledge, you can explore more advanced use cases and build powerful applications using child processes in Node.js.

Stay tuned for more exciting Node.js tutorials!

#NodeJS #ChildProcesses