js获取元素class的几种方法

1.

       function getByClass(classname){

                var nodes = document.getElementsByTagName('*'),

                     ret=[];

                for(var i=0;i<nodes.length;i++){

                       if(hasClass(nodes[i],classname))

                          ret.push(nodes[i]);

                }

                return ret;

            }

            function hasClass(node,className){

                var names = node.className.split(/\s+/);

                for(var i=0;i<names.length;i++){

                    if(names[i]==className)

                        return true;

                }return false;

            }

2.

<script language="javascript">
window.onload=function(){
 //用className读取元数
function getClass(className,outId){
 element=document.getElementById('outId')||document;
 var temobj=element.getElementsByTagName('*')||document.all;
 classnames=[];
 for(var i=0;i<temobj.length;i++){
  var child=temobj[i];
  var classname=child.className.split(' ');
  for(var j=0;j<classname.length;j++){
   if(classname[j]==className){
    classnames.push(child);
    break;
    }
   }
  }
  return classnames;
 }
 //调用方法
 var on=getClass('tow','list');
 alert(on[0].innerHTML);
 }
</script>

3.