if(document.getElementsByClassName) {

    getElementsByClass = function(classList, node) {    
        //return (node || document).getElementsByClassName(classList)
        return document.getElementsByClassName(classList)
    }

} else {

    getElementsByClass = function(classList, node) {            
        var node = node || document,
        list = document.getElementsByTagName('*'), 
        length = list.length,  
        classArray = classList.split(/\s+/), 
        classes = classArray.length, 
        result = [], i,j
        for(i = 0; i < length; i++) {
            for(j = 0; j < classes; j++)  {
                if(list[i].className.search('\\b' + classArray[j] + '\\b') != -1) {
                    result.push(list[i])
                    break
                }
            }
        }
    
        return result
    }

}