Sleep function in javaScript

JavaScript provides setTimeout() and setInterval() methods to delay execution of script. But, it doesn't provide any way to sleep execution at a single line. Let's build our custom sleep method.

TOC

1. Prerequisites
2. idea
3. sleep API
4. uses
5. live interactive demo

Prerequisites

• Promise
• async
• await
• setTimeout

I am assuming that you know the above prerequisites.

Idea is to use a promise to wait for a number of milliseconds. We know, we can delay the execution of certain script using await. Using await we can run the next script after the promise is resolved or rejected.

Let's build our sleep API

function sleep(ms){  return new Promise((resolve)=>{    setTimeout(()=>resolve(),ms);  })}

The above sleep API will wait for some milliseconds, then it resolves the promise.

Uses

make sure to call this API inside the async function

async function test(){    // wait for 3 seconds    console.log("Waiting...");    await sleep(3000);     console.log("The wait is over");}

Live demo

See the Pen oNzpMZN by Rahul kumar
(@ats1999) on CodePen.