get element by class name

getElementsByClassName.js

function getElementsByClassName(classname, node) {

	if(!node) node = document.getElementsByTagName("body")[0];

	var a = [];

	var re = new RegExp('\\b' + classname + '\\b');

	var els = node.getElementsByTagName("*");

	for(var i=0,j=els.length; i<j; i++)

	if(re.test(els[i].className))a.push(els[i]);

	return a;

}