Simple animation

Details
Written by: Stanko Milosev
Category: JavaScript
Hits: 5126

HTML:

<!DOCTYPE html>
<html>

	<head>
		<link type="text/css" rel="stylesheet" href="/index.css">
		<script type="text/javascript" src="/index.js"></script>
	</head>
	
	<body>
		<div class="animation"></div>
	</body>
	
</html>

JS:

var spritePosition,
	imageLeft, 
	imageTop,
	step;

window.onload = function () {
	spritePosition = 100;
	imageLeft = 0;
	imageTop = 0;
	step = 10;
	
	window.setInterval (function () {
		document.getElementsByClassName('animation')[0].style.backgroundPosition = spritePosition + "px 0px";
		spritePosition = spritePosition + 108;
	}, 100);
	
	document.getElementsByTagName('html')[0].addEventListener("keydown", function(e){ 
			if (e.keyCode == 38) { //up
				imageTop = imageTop - step;
				document.getElementsByClassName('animation')[0].style.top = imageTop + "px";
			};
			if (e.keyCode == 40) { //down
				imageTop = imageTop + step;
				document.getElementsByClassName('animation')[0].style.top = imageTop + "px";
			};
			if (e.keyCode == 37) { //left
				imageLeft = imageLeft - step;
				document.getElementsByClassName('animation')[0].style.left = imageLeft + "px";
			};
			if (e.keyCode == 39) { //right
				imageLeft = imageLeft + step;
				document.getElementsByClassName('animation')[0].style.left = imageLeft + "px";
			};			
		}, false);
};

Things to notice in JS code are window.setInterval - with that we have infinite loop, and document.getElementsByTagName('html')[0].addEventListener("keydown", function(e){ - with that we are listening key events, so you can move image around page.

CSS:

.animation {
	width: 102px;
	height: 120px;
	background-image: url("scottpilgrim_multiple.png");
	background-position: 0px 0px;
	position: absolute;
}

Sprite I have stolen from this web site, and example you can download from here.