javscript操作Select标签[动态添加，清空]

<! DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd" >
< html  xmlns ="http://www.w3.org/1999/xhtml" >
< head >
< meta  http-equiv ="Content-Type"  content ="text/html; charset=gb2312"   />
< title > 无标题文档 </ title >
< script  type ="text/javascript" >
function addList(){
    var list = document.getElementById("list");
    for(var i = 1; i <= 5; i++){
        var newOption = document.createElement("option");
        newOption.setAttribute("value", i);
        newOption.appendChild(document.createTextNode("测试数据" + i));
        list.appendChild(newOption);
    }
}

function clearList(){
    var list = document.getElementById("list");
    
    for(var i = list.options.length; i >= 0; i--){
        list.remove(i);
    }
    //注意：每删除一个option其它option的index特性会自动重置，因此，按以下方法(即从上往下删是清除不了的)
    //for(var i = 0; i< list.options.length; i++){
    //    list.remove(i);
    //}
}
</ script >
</ head >
< body >
< select  name ="list"  id ="list" >
</ select >
< input  type ="button"  onclick ="addList()"   value ="生成" />
< input  type ="button"  onblur ="clearList()"  value ="清空"   />
</ body >
</ html >