Chain Async Functions

Introduction

In this lab, we will explore how to chain asynchronous functions in JavaScript. We will learn how to loop through an array of functions containing asynchronous events and call the next function when each event has completed. By the end of the lab, you will be able to efficiently execute a series of asynchronous operations in a specific order.

Chaining Asynchronous Functions

To chain asynchronous functions, open the Terminal/SSH and type node. Then, loop through an array of functions containing asynchronous events, and call the next function when each asynchronous event has completed.

Here's a code snippet that demonstrates how to chain asynchronous functions:

const chainAsync = (fns) => {
  let curr = 0;
  const last = fns[fns.length - 1];
  const next = () => {
    const fn = fns[curr++];
    fn === last ? fn() : fn(next);
  };
  next();
};

chainAsync([
  (next) => {
    console.log("0 seconds");
    setTimeout(next, 1000);
  },
  (next) => {
    console.log("1 second");
    setTimeout(next, 1000);
  },
  () => {
    console.log("2 second");
  }
]);

Summary

Congratulations! You have completed the Chain Async Functions lab. You can practice more labs in LabEx to improve your skills.