Retrieving requestAnimationFrame with JavaScript
The requestAnimationFrame function has been a major boost to developers creating and managing animations with JavaScript. Paul Irish has an excellent introduction on requestAnimationFrame -- I highly recommend you read it. This HTML5Hub post is also very good. Most browsers now support the animation function but in the case a browser doesn't, you can shim a rough equivalent with setInterval:
var requestAnimationFrame = window.requestAnimationFrame
|| window.webkitRequestAnimationFrame
|| window.mozRequestAnimationFrame
|| window.msRequestAnimationFrame
|| function(callback) { return setTimeout(callback, 1000 / 60); };
requestAnimationFrame was implemented with browser prefixes so we'll check for those if the unprefixed window method isn't there. If no native implementation exists, a setInterval shim will have to do!
![Write Better JavaScript with Promises]()
You've probably heard the talk around the water cooler about how promises are the future. All of the cool kids are using them, but you don't see what makes them so special. Can't you just use a callback? What's the big deal? In this article, we'll...
![9 Mind-Blowing Canvas Demos]()
The <canvas> element has been a revelation for the visual experts among our ranks. Canvas provides the means for incredible and efficient animations with the added bonus of no Flash; these developers can flash their awesome JavaScript skills instead. Here are nine unbelievable canvas demos that...
![Introducing MooTools HeatMap]()
It's often interesting to think about where on a given element, whether it be the page, an image, or a static DIV, your users are clicking. With that curiosity in mind, I've created HeatMap: a MooTools class that allows you to detect, load, save, and...
![WordPress-Style Comment Controls Using MooTools or jQuery]()
WordPress has a nice little effect on the Admin Dashboard where it shows and hides the comment control links when you mouseover and mouseout of the record's container. Here's how to achieve that effect using MooTools or jQuery.
The XHTML
Notice that we place the links into...
According to caniuse, Microsoft’s browsers never had a vendor prefixed version of
requestAnimationFrame, so we can just keepmozandwebkit.That’s a very common way to normalize the function, but in most recent implementations
requestAnimationFramepasses an argument to the callback function, which is the amount of milliseconds sinceperformance.timing.navigationStart, with micro precision too. This can be very handy for the callback.It’s not really possible to perfectly emulate this, but you can get something close if you take note of the epoch time as soon as the script is executed. So this is how I used to polyfill
requestAnimationFrame:(function(start) { window.requestAnimationFrame = function(callback) { return setInterval(function() { callback(new Date().getTime() - start); }, 1000 / 60); }; })(new Date().getTime());(Well, not exactly… since most of the times
requestAnimationFrameis called again in the callback function, but the function itself takes some milliseconds at least to be executed – because it probably involves some kind of repaint – and you should adjust the time interval accordingly, or you may never hope to even get close to 60 fps.)Also, don’t forget to normalize
cancelAnimationFrame, which has a nasty variant in some (and maybe forgotten?) WebKit browsers:webkitCancelRequestAnimationFrame.