delay between actions

Is there a way I can do a sleep in JavaScript before it carries out another action?

Example:

 var a = 1+3;
 // Sleep 3 seconds before the next action here
 var b = a + 4;

---

You can use setTimeout to achieve a similar effect:

var a = 1 + 3;
var b;
setTimeout(function() {
    b = a + 4;
}, (3 * 1000));

This doesn't really 'sleep' JavaScript—it just executes the function passed to setTimeout after a certain duration (specified in milliseconds). Although it is possible to write a sleep function for JavaScript, it's best to use setTimeout if possible as it doesn't freeze everything during the sleep period.

---

In case you really need a sleep() just to test something. But be aware that it'll crash the browser most of the times while debuggin - probably that's why you need it anyway. In production mode I'll comment out this function.

function pauseBrowser(millis) {
    var date = Date.now();
    var curDate = null;
    do {
        curDate = Date.now();
    } while (curDate-date < millis);
}

Don't use new Date() in the loop, unless you want to waste memory, processing power, battery and possibly the lifetime of your device.

---

ECMAScript 6 version, using generators with yield for "code blocking":

Because the original question was posted seven years ago, I didn't bother answering with the exact code, because it's just way too easy and already answered. This should help in more complicated problems, like if you need at least two sleeps, or if you are planning to sequence asynchronous execution. Feel free to modify it to fit your needs.

let sleeptime = 100
function* clock()
{
    let i = 0
    while( i <= 10000 )
    {
        i++
        console.log(i); // actually, just do stuff you wanna do.
        setTimeout(
            ()=>
            {
                clk.next()
            }
            , sleeptime
        )
        yield
    }
}

let clk = clock()
clk.next()

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