How to sleep() in JavaScript

Introduction

Sometimes, we may wish to sleep() for a specific period in a JavaScript program. In this post, we'll learn how to do it.

How to hold running JavaScript program for a specific time (alternative to sleep() function in other programming languages)

To sleep() your application in JavaScript you can use Promise, setTimeout() and await:

const sleep = ms => new Promise(r => setTimeout(r, ms));

This sleep() function will hold the running program for a given period in milliseconds.

await sleep(<duration>); // duration in milliseconds

If you want to run code after a specific time you can use the following code:

sleep(500).then(() => {
    // Do something after sleep!
});

In case you don't want to use the setTimeout() function you can use the following:

function sleep(duration) {
    var now = new Date().getTime();
    while(new Date().getTime() < now + duration) { 
       /* Do nothing */ 
    }
}

sleep(2000);
console.log("Hello, FrontBackend after sleep!");

Conclusion

In this post, we presented the best way to sleep() in JavaScript.