Is there a sleep function in javascript?

Question

Is there a sleep function in javascript?

Answer 1

You can use the setTimeout or setInterval functions.

Answer 2

If you are looking to block the execution of code with call to 'sleep', then no, there is no method for that in JavaScript.

JavaScript does have setTimeout method. setTimeout will let you defer execution of a function for x milliseconds. E.g.

setTimeout(myFunction, 3000);// if you have defined a function named myFunction it will run after 3 seconds (3000 milliseconds)

Remember, this is completely different from how 'sleep' method, if it existed, would behave.

function test1()
{

   //some code

   //Let's say JS did have a sleep function.
   sleep(3000); //sleep for 3 seconds, 

   alert('hi'); 
}

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'. Unfortunately, there is no sleep function like that in JavaScript.

function test2()
{
    setTimeout(function() { alert('hello');}, 3000); //defer the execution of anonymous function for 3 seconds and go to next line of code. 

    alert('hi');
}

If you run test2, you will see 'hi' right away (setTimeout is non blocking) and after 3 seconds you will see the alert 'hello'.