/*
 *  Refactored & improved in 2011 by Tubal Martin (http://www.margenn.com)
 *  Unit tests: http://www.margenn.com/tubal/javascript/getelementsbyclassname.html
 *  Original version developed by Robert Nyman in 2008 http://code.google.com/p/getelementsbyclassname/
 */	
var getElementsByClassName = document.getElementsByClassName ?
    function (className, tag, elm) {
        var nodeElm = elm && elm.getElementsByClassName ? elm : document,
            elements = nodeElm.getElementsByClassName(className),
            nodeName = tag ? new RegExp("\\b" + tag + "\\b", "i") : null,
            rElements = [],
            i = 0, l = elements.length,
            current;
        for (; i < l; i++) {
            current = elements[i];
            if (!nodeName || nodeName.test(current.nodeName)) {
                rElements.push(current);
            }
        }
        return rElements;
    } : document.querySelectorAll ?
    function (className, tag, elm) {
        var elements = (elm || document).querySelectorAll((tag || "") + "." + className.split(" ").join(".")),
            rElements = [], 
            i = 0, l = elements.length;
        for (; i < l; i++) {
            rElements.push(elements[i]);
        }
        return rElements;
    } : document.evaluate ?
    function (className, tag, elm) {
        var classes = className.split(" "),
            classesToCheck = "",
            rElements = [],
            i = 0, l = classes.length, 
            elements, node;
        for(; i < l; i++){
            classesToCheck += "[contains(concat(' ', normalize-space(@class), ' '), ' " + classes[i] + " ')]";
        }
        elements = document.evaluate(".//" + (tag || "*") + classesToCheck, (elm || document), null, 0, null);
        while (node = elements.iterateNext()) {
            rElements.push(node);
        }
        return rElements;
    } :
    function (className, tag, elm) {
        tag = tag || "*";
        elm = elm || document;
        var classes = className.split(" "),
            classesToCheck = [],
            elements = tag == "*" && elm.all ? elm.all : elm.getElementsByTagName(tag),
            rElements = [],
            i = j = 0, 
            il = classes.length, 
            jl = elements.length,
            current, match, k, kl;
        for (; i < il; i++) {
            classesToCheck.push(new RegExp("(^|\\s)" + classes[i] + "(\\s|$)"));
        }
        kl = classesToCheck.length;
        for (; j < jl; j++) {
            current = elements[j];
            match = false;
            for (k = 0; k < kl; k++) {
                match = classesToCheck[k].test(current.className);
                if (!match) {
                    break;
                }
            }
            if (match) {
                rElements.push(current);
            }
        }
        return rElements;
    };