JavaScript sleep/wait before continuing
How can you make JavaScript wait or sleep before executing the next line of code?
This question explores ways to pause execution in JavaScript using methods like setTimeout, Promises, or async/await to control timing in your code.
In JavaScript, there isn’t a built-in sleep() function like in some other programming languages, but you can still pause or delay execution using some clever tricks — especially with modern async/await syntax. So, if you're wondering how to make your code wait before moving on, here are a few ways to do it:
1. Using setTimeout()
This is the most basic approach. It sets a timer and runs a function after a specified delay.
setTimeout(() => {
console.log("This runs after 2 seconds");
}, 2000);But remember — this doesn’t actually pause your code, it just schedules something for later.
2. Using async/await with Promises
If you want your code to wait properly, this is the way to go:
function sleep(ms) {
return new Promise(resolve => setTimeout(resolve, ms));
}
async function example() {
console.log("Wait for it...");
await sleep(2000);
console.log("2 seconds later!");
}
example();3. Why not a loop?
You might be tempted to use a while loop to create a delay, but this can freeze your browser or app:
// BAD practice – blocks everything
let start = Date.now();
while (Date.now() - start < 2000>Summary:
- Use setTimeout() for non-blocking delays.
- Use async/await + Promises for actual pause-and-resume behavior.
- Avoid blocking loops!