js 操作select與option(示例講解)

2019-11-20 21:25:22

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1.動態創建select

function createSelect(){

var mySelect = document.createElement_x("select");
          mySelect.id = "mySelect";
          document.body.appendChild(mySelect);
      }

2.添加選項option

復制代碼代碼如下:

function addOption(){

//根據id查找對象，
var obj=document.getElementByIdx_x('mySelect');

           //添加一個選項
obj.add(new Option("文本","值"));    //這個只能在IE中有效
         obj.options.add(new Option("text","value")); //這個兼容IE與firefox
     }

3.刪除所有選項option

復制代碼代碼如下:

function removeAll(){
var obj=document.getElementByIdx_x('mySelect');
obj.options.length=0;

}

4.刪除一個選項option

復制代碼代碼如下:

function removeOne(){
var obj=document.getElementByIdx_x('mySelect');

//index,要刪除選項的序號，這里取當前選中選項的序號

var index=obj.selectedIndex;
obj.options.remove(index);
}

5.獲得選項option的值

var obj=document.getElementByIdx_x('mySelect');
var index=obj.selectedIndex; //序號，取當前選中選項的序號
var val = obj.options[index].value;

6.獲得選項option的文本

var obj=document.getElementByIdx_x('mySelect');
var index=obj.selectedIndex; //序號，取當前選中選項的序號
var val = obj.options[index].text;

7.修改選項option

var obj=document.getElementByIdx_x('mySelect');
var index=obj.selectedIndex; //序號，取當前選中選項的序號
var val = obj.options[index]=new Option("新文本","新值");

8.刪除select

復制代碼代碼如下:

function removeSelect(){
var mySelect = document.getElementByIdx_x("mySelect");
mySelect.parentNode.removeChild(mySelect);
     }

整個實例的完整代碼如下：

復制代碼代碼如下:

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//ZH-CN" "http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
   <meta http-equiv="Content-Type" content="text/html">
<head>
   <script language=JavaScript>
    function $(id)
    {
     return document.getElementByIdx_x(id)
    }
    function show()
    {
     var selectObj=$("area")
     var myOption=document.createElement_x("option")
     myOption.setAttribute("value","10")
     myOption.appendChild(document.createTextNode("上海"))
     var myOption1=document.createElement_x("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_x("select")
      sh.add(new Option("浦東新區","101"))
      sh.add(new Option("黃浦區","102"))
      sh.add(new Option("徐匯區","103"))
      sh.add(new Option("普陀區","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_x("select")
      nj.add(new Option("玄武區","201"))
      nj.add(new Option("白下區","202"))
      nj.add(new Option("下關區","203"))
      nj.add(new Option("棲霞區","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="顯示" onclick="show()">
<input type=button value="計算結點" onclick="calc()">
<input type=button value="刪除" onclick="remove()">
</body>
</html>

改進版：在select中添加、修改、刪除option元素

復制代碼代碼如下:

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

但上述 add() 方法只在IE下有效，為兼容FF和Opera，對上述代碼進行了一下改進，改動后代碼如下：

復制代碼代碼如下:

function watch_ini(){ // 初始
for(var i=0; i<arguments.length; i++){
   var oOption=new Option(arguments[i],arguments[i]);
   document.getElementByIdx_x("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;
}

整個實例的完整代碼如下：

復制代碼代碼如下:

<!doctype html public "-//w3c//dtd html 4.0 transitional//en">
<html>
<head>
<title>javascript select options text value</title>
<meta name="keywords" content="javascript select options text value add modify delete set">
<meta name="description" content="javascript select options text value add modify delete set">
<script language="javascript">

</script>
</head>
<body>
<form name="watch" method="post" action="">
<select id="MySelect" name="keywords" size="10" onchange="watch_sel(this.form)"></select><br>
<script language="javascript">
<!--
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