Question

I have been experimenting a lot with setInterval and clearInterval recently, for creating my own custom effects and one of the things that I have been working on is an efficient way to clear an interval whilst staying out of the global scope. I am trying to improve readability and explore possible performance boosts by using .promise() to call clearInterval() (the below is an example of what I’m trying to do):

//caller is a collection of elements
function performEffect(caller) {
   var interval = setInterval(function() { caller.next(); }, 500);
   caller.promise().done(function() { interval = clearInterval(interval); });
}

Up until recently, I had been setting and clearing the interval using an embedded function (example):

function performEffect(caller) {
   var interval;
   var count = 0;
   var len = caller.length;

   if (count >= len) {
       interval = clearInterval(interval);
   }

   var tmr = function () {
       interval = setInterval(function () { effectFunciton(count++); }, 100);
   }
}

P.S. I’m sorry for not posting the original – my versioning system was corrupted. Also, I know that this example is kind of silly, since I could easily use a for-loop or a .each(), but it’s just an example – I do have instances where I do not want to use a loop.

This is my first post, so I apologize ahead of time if I do something different from the accepted practice. Please let me know if there is anything I can do to improve my posts in the future – I’m always open to constructive criticism 🙂

Thanks!

Answer 1

You’ll want to use deferreds for this. I wrote an example on jsfiddle a little while ago that may give you some insight.

http://jsfiddle.net/landau/M3Lj4/

From your code, it looks like you are misunderstanding deferreds in general or there isn’t enough code here to tell what you are doing. Promises hides resolving and rejecting functionality

Basically,

var deferred = $.Deferred();
var promise = deferred.promise();

// This will only run once
var timer = setInterval( function () {
    deferred.resolve();
}, 1000);

promise.done(function () {
    clearInterval( timer );
});