Here, we are creating a promise with the setTimeout() function. The loop will iterate 10 times with a pause of 2 seconds on every iteration. Return new Promise(resolve => setTimeout(resolve, milliseconds)) Īfter the execution of the above code, the output will be -Īfter two seconds, the output will change. How to use sleep function in JavaScript?īefore implementing the sleep function in JavaScript, it is important to understand the execution of the JavaScript code. Async/await functions help us to write the code in a synchronous manner.

Because of this asynchronous behavior, it continues its work and does not wait for anything during execution. The behavior of JavaScript is asynchronous, so there is a concept of promises to handle such asynchronous behavior. The await is used to wait for a promise and can only be used in an async function. The features such as promises and async/await function in JavaScript helped us to use the sleep() function in an easier way. We can use some approaches for simulating the sleep() function in JavaScript. Unlike other languages, JavaScript doesn't have any sleep() function. Java has a thread.sleep(), python has time.sleep(), and GO has time.sleep(2*cond). If you run test2, you will see 'hi' right away ( setTimeout is non blocking) and after 3 seconds you will see the alert 'hello'.The programming languages such as PHP and C has a sleep(sec) function to pause the execution for a fixed amount of time.

3 seconds and go to next line of code. defer the execution of anonymous function for Unfortunately, there is no sleep function like that in JavaScript. If you run the above function, you will have to wait for 3 seconds ( sleep method call is blocking) before you see the alert 'hi'. let's say JavaScript did have a sleep function. Remember, this is completely different from how sleep method, if it existed, would behave. it will run after 3 seconds (3000 milliseconds) if you have defined a function named myFunction setTimeout will let you defer execution of a function for x milliseconds. If you are looking to block the execution of code with call to sleep, then no, there is no method for that in JavaScript.

Time sleep javascript