20150629 关于ie下getElementsByClassName的兼容

//兼容ie低版本getElementsByClassName的方法
if(!document.getElementsByClassName){
    document.getElementsByClassName=function(classname){
        var children=document.getElementsByTagName(‘*‘);
        var elements=[];
        for(var i= 0,len=children.length;i<len;i++){
            for(var j= 0,jlen=children[i].className.split(‘ ‘);j<jlen.length;j++){
                if(jlen[j]==classname){
                    elements.push(children[i]);
                    break;
                }
            }
        }
        return elements;
    }
}