js获取封装对象/通过id tag className

<script language="javascript" type="text/javascript">
/*-------------封装开始------------------*/
function GetId(id){return document.getElementById(id)}  //通过ID获取对象
function GetTag(tag){return document.getElementsByTagName(tag)}  //通过Tag获取对象
function GetChildTag(id,tag){return id.getElementsByTagName(tag)}  //通过Tag获取ID的子对象
function GetClass(className){return getElementsByClassName(className)}  //通过className获取对象
var $c=function(array){var nArray = [];for (var i=0;i<array.length;i++) nArray.push(array[i]);return nArray;};
Array.prototype.each=function(func){for(var i=0,l=this.length;i<l;i++) {func(this[i],i);};};
var getElementsByClassName=function(cn){
var hasClass=function(w,Name){
var hasClass = false;
w.className.split(' ').each(function(s){
if (s == Name) hasClass = true;
});
return hasClass;
};
var elems =document.getElementsByTagName("*")||document.all;
var elemList = [];
$c(elems).each(function(e){
if(hasClass(e,cn)){elemList.push(e);}
})
return $c(elemList);
};
/*-----------------封装结束---------------------*/
window.onload=function(){
GetTag("input")[0].onclick=function(){alert("id为test的div内容是：\n"+GetId("test").innerHTML)}
GetTag("input")[1].onclick=function(){alert("body里共有"+GetTag("li").length+"个li")}
GetTag("input")[2].onclick=function(){alert("DIV里共有"+GetChildTag(GetId("test"),"li").length+"个li")}
GetTag("input")[3].onclick=function(){alert("className为test2的内容是：\n"+GetClass("test2")[0].innerHTML+"\n"+GetClass("test2")[1].innerHTML)}
}
</script>

<div id="test" title="这是id=test的div">
<ul title="div内第一个ul">
<li>ccontent1</li>
<li>ccontent2</li>
<li>ccontent3</li>
<li>ccontent4</li>
</ul>
<ul class="test2" title="div内第二个ul，class=test2">
<li>bcontent1</li>
<li>bcontent2</li>
<li>bcontent3</li>
</ul>
</div>
<ul class="test2" title="div外的ul，class=test2">
<li>content1</li>
<li>content2</li>
</ul>
<input type="button" value="通过id获取" />
<input type="button" value="通过tag获取" />
<input type="button" value="通过id内tag获取" />
<input type="button" value="通过className获取" />