time delay between 2 lines of code in javascript, not settimeout

Question

is there a function that would add a time delay between 2 lines of code. Not the settimeout, because settimeout requires a function/object in its arguments.

I am looking for something like this pseudo code

write "abc";
delay(500);
write "xyz";

TIA

Edit: jimr's solution in my other thread worked for my purpose, and so is Robusto's.

I am just wondering why the "sleep" methods given by Robusto and CMS's link are not preferred. How would that be different than the settimeout method since they both introduce a pause in the code? (settimeout pauses before the function is executed, the sleep method pauses before the next line is executed.)

Answer 1

As far as I know, setTimeout() is the only way to do it.

function write(out) {
  alert(out);
}

// ...

write('abc');
setTimeout(function() { write('xyz')}, 500);

Answer 2

A sleep-Method is not available because JavaScript execution blocks the browser, so a sleep-Method would block the browser for 500msec, do you really want to have your browser not responding for half an second?

Use setTimeout as suggested.

Answer 3

You can use setTimeout so that it almost appears the code runs on two lines:

write('abc')
setTimeout(function() {
write('xyz')
},500)

Answer 4

The following is clunky and ugly, but it should work for what you want.

// time arg is in milliseconds
function delay(time) {
  var d1 = new Date();
  var d2 = new Date();
  while (d2.valueOf() < d1.valueOf() + time) {
    d2 = new Date();
  }
}

Answer 5

I don't know what you're trying to do here, but here's one concrete reason for why a custom sleep may not work for your purposes assuming the browser freezing up is a non-issue for you.

Are you manipulating the DOM by any chance between those two write commands? If you are, then it simply will not work (as perceived by an end user), although the DOM nodes will be constructed/updated in memory, the display will not get updated as that part is not synchronous. The processor is locked up in that loop, and both the DOM updates will refresh on screen when that loop finishes. See this example.

Ideally, you should see "Hello", and after 5 seconds, "World" on the screen. However, on Chrome, Safari, and Firefox, you would see both "Hello" and "World" at the end of 5 seconds. The console logs prove that the DOM node is constructed in memory, but is not refreshed on screen until the end as you can see yourself.

Answer 6

In JavaScript 1.7, using yield with async.js, you can do the following:

var yourFunction = _(function () {
    write("abc");
    yield to.sleep(.500);
    write("xyz");
});