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!
![5 More HTML5 APIs You Didn’t Know Existed]()
The HTML5 revolution has provided us some awesome JavaScript and HTML APIs. Some are APIs we knew we've needed for years, others are cutting edge mobile and desktop helpers. Regardless of API strength or purpose, anything to help us better do our job is a...
![CSS Animations Between Media Queries]()
CSS animations are right up there with sliced bread. CSS animations are efficient because they can be hardware accelerated, they require no JavaScript overhead, and they are composed of very little CSS code. Quite often we add CSS transforms to elements via CSS during...
![Fullscreen API]()
As we move toward more true web applications, our JavaScript APIs are doing their best to keep up. One very simple but useful new JavaScript API is the Fullscreen API. The Fullscreen API provides a programmatic way to request fullscreen display from the user, and exit...
![Detect DOM Node Insertions with JavaScript and CSS Animations]()
I work with an awesome cast of developers at Mozilla, and one of them in Daniel Buchner. Daniel's shared with me an awesome strategy for detecting when nodes have been injected into a parent node without using the deprecated DOM Events API.
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.