js 操作select下option

沐浴中的眼泪 2011-01-11

展开全文

注意:Option中的O是要大写的，不然语法报错

1.动态创建select
Javascript代码
function createSelect(){
    var mySelect = document.createElement("select");
    mySelect.id = "mySelect";
    document.body.appendChild(mySelect);
}

2.添加选项option
Javascript代码
     function addOption(){
           var obj=document.getElementById('mySelect');
           obj.add(new Option("文本","值"));    //这个只能在IE中有效
           obj.options.add(new Option("text","value")); //这个兼容IE与firefox

            var op=document.createElement("option");
            op.text=clos[i];
            op.value=clos[i];
            //sel.options.add(new Option(clos[i],clos[i]));
            sel.options.add(op);
     }
----------------------------------------------------------------
Option里面的四个参数分别的意思
new   Option   (text,value,defaultselected,selected)
new   Option   (文本,值,默认选中的选项,选中的选项)
看测试结果就懂了
<select   id="s1"></select>
<script>
      var   op   =   new   Option("显示文本1","值1",false,false);
      s1.options.add(op);
      op   =     new   Option("显示文本2","值2",false,true);
      s1.options.add(op);
</script>
-----------------------------------------------------------------
3.删除所有选项option
Javascript代码
     function removeAll(){
           var obj=document.getElementById('mySelect');
           obj.options.length=0;
     }
4.删除一个选项option
Javascript代码
function removeOne(){
           var obj=document.getElementById('mySelect');
           //index,要删除选项的序号，这里取当前选中选项的序号
          var index=obj.selectedIndex;
          obj.options.remove(index);
     }
5.获得选项option的值
Javascript代码
var obj=document.getElementById('mySelect');
var index=obj.selectedIndex; //序号，取当前选中选项的序号
var val = obj.options[index].value;
6.获得选项option的文本
Javascript代码
var obj=document.getElementById('mySelect');
var index=obj.selectedIndex; //序号，取当前选中选项的序号
var val = obj.options[index].text;
7.修改选项option
Javascript代码
var obj=document.getElementById('mySelect');
var index=obj.selectedIndex; //序号，取当前选中选项的序号
var val = obj.options[index]=new Option("新文本","新值");
8.删除select
Javascript代码
      function removeSelect(){
            var mySelect = document.getElementById("mySelect");
           mySelect.parentNode.removeChild(mySelect);
     }
整个实例的完整代码如下：

Javascript代码
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//ZH-CN" "http://www./TR/html4/strict.dtd">
<html>
<head>
   <meta http-equiv="Content-Type" content="text/html">
<head>
   <script language=JavaScript>
    function $(id)
    {
     return document.getElementById(id)
    }
    function show()
    {
     var selectObj=$("area")
     var myOption=document.createElement("option")
     myOption.setAttribute("value","10")
     myOption.appendChild(document.createTextNode("上海"))
     var myOption1=document.createElement("option")
     myOption1.setAttribute("value","100")
     myOption1.appendChild(document.createTextNode("南京"))
     selectObj.appendChild(myOption)
     selectObj.appendChild(myOption1)
    }
    function choice()
    {
     var index=$("area").selectedIndex;
     var val=$("area").options[index].getAttribute("value")
     if(val==10)
     {
      var i=$("context").childNodes.length-1;
     var remobj=$("context").childNodes[i];
     remobj.removeNode(true)
      var sh=document.createElement("select")
      sh.add(new Option("浦东新区","101"))
      sh.add(new Option("黄浦区","102"))
      sh.add(new Option("徐汇区","103"))
      sh.add(new Option("普陀区","104"))
      $("context").appendChild(sh)
     }
     if(val==100)
     {
      var i=$("context").childNodes.length-1;
     var remobj=$("context").childNodes[i];
     remobj.removeNode(true)
      var nj=document.createElement("select")
      nj.add(new Option("玄武区","201"))
      nj.add(new Option("白下区","202"))
      nj.add(new Option("下关区","203"))
      nj.add(new Option("栖霞区","204"))
      $("context").appendChild(nj)
     }
    }
    function calc()
    {
     var x=$("context").childNodes.length-1;
     alert(x)
    }
    function remove()
    {
     var i=$("context").childNodes.length-1;
     var remobj=$("context").childNodes[i];
     remobj.removeNode(true)
    }
   </script>
<body>
<div id="context">
   <select id="area" onchange="choice()">
   </select>
</div>
<input type=button value="显示" onclick="show()">
<input type=button value="计算结点" onclick="calc()">
<input type=button value="删除" onclick="remove()">
</body>
</html>

改进版：在select中添加、修改、删除option元素

Javascript代码
function watch_ini(){ // 初始
for(var i=0; i<arguments.length; i++){
var word = document.createElement("OPTION");
word.text = arguments[i];
watch.keywords.add(word); // watch. is form name
}
}
function watch_add(f){ // 增加
var word = document.createElement("OPTION");
word.text = f.word.value;
f.keywords.add(word);
}

但上述 add() 方法只在IE下有效，为兼容FF和Opera，对上述代码进行了一下改进，改动后代码如下： function watch_ini(){ // 初始

Javascript代码
for(var i=0; i<arguments.length; i++){
   var oOption=new Option(arguments[i],arguments[i]);
   document.getElementById("MySelect")[i]=oOption;
}
}
function watch_add(f){ // 增加
   var oOption=new Option(f.word.value,f.word.value);
   f.keywords[f.keywords.length]=oOption;
}