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In Node.js, the term multithreading does not apply because Node.js is designed to run in a single-threaded event loop. However, Node.js is built on top of the JavaScript language, which is single-threaded by default.

However, Node.js provides some ways to perform concurrent programming tasks. One way is to use child_processthe module, which allows you to spawn new processes that can run concurrently with the main Node.js process.

Another way to perform concurrent tasks in Node.js is to use async/awaitthe syntax, which allows you to write asynchronous code that looks like synchronous code. This makes it easier to write code that performs multiple tasks at the same time without explicitly spawning new processes or using callbacks.

For example, the following code uses async/await to execute two tasks simultaneously.

async function runTasks() {
  const task1 = doTask1();
  const task2 = doTask2();

  await Promise.all([task1, task2]);
}

In this example, doTask1 and doTask2 are asynchronous functions that return Promises. awaitThe operator is used to wait for both Promises to resolve before continuing.

This allows the two tasks to execute concurrently rather than sequentially. It’s worth noting that async/awaitthe syntax is built on top of the JavaScript Promise type, which allows us to write asynchronous code in a way that looks more like traditional synchronous code.

The spawn module in Node.js child_processprovides an easy way to spawn new processes. It allows you to run external programs, such as Bash scripts or other executables, from within a Node.js program.

Implementing multithreading in Node.js

Below is child_processan example of running a Bash script using the module.

In this example, execa function is used to execute a Bash script named bash_script.sh . The function takes a callback that is called when the process completes.

The callback receives three arguments: error , stdout , and stderr . These arguments contain the error that occurred, the process's standard output, and the process's standard error, respectively.

child_processThe module provides several other functions for spawning processes, such as spawn , fork , and execFile . Each of these functions has its own set of options and behavior, so you can choose the one that best suits our needs.

const { exec } = require("child_process");

exec("bash_script.sh", (error, stdout, stderr) => {
  if (error) {
    console.error(`exec error: ${error}`);
    return;
  }
  console.log(`Script run successfully`);
});

The output is as follows:

stdout:
stderr:
Script run successfully