function getElementsByClassName(clsName,htmltag,root){    
    var arr = new Array();   
    var obj = document.getElementById(root);   
    var elems = obj.getElementsByTagName(htmltag);   
    for ( var cls, i = 0; ( elem = elems[i] ); i++ ){   
        if ( hasClass(clsName,elem) ) {   
            arr[arr.length] = elem;   
        }   
    }   
    return arr;   
}
function hasClass(clsName,elem) {   
    var re;   
    var str = elem.className;   
    re = new RegExp('(?:^|\\s+)' + clsName + '(?:\\s+|$)') ;   
    return re.test(str) ? 1 : 0 ;   
}