用JS和C#分别在前端和后端控制下拉框为只读的方法_JavaScript

下拉框只读此功能并不是默认的，需要手动操作下，本文介绍用JS和C#分别在前端和后端控制下拉框为只读的方法

前端JavaScript的方法

<HTML> 
<HEAD> 
<TITLE>下拉框模拟只读</TITLE> 
<script type="text/javascript"> 
//根据下拉框ID设置下拉框只读 
function setReadOnly(obj_id){ 
var obj = document.getElementById(obj_id); 
obj.onmouseover = function(){ 
obj.setCapture(); 
} 
obj.onmouseout = function(){ 
obj.releaseCapture(); 
} 
obj.onfocus = function(){ 
obj.blur(); 
} 
obj.onbeforeactivate = function(){ 
return false; 
} 
} 
</script> 
</HEAD> 
<BODY> 
<span id="span_select"> 
<select id="id_select"> 
<option value="1">AAAAAAAAA</option> 
<option value="2">BBBBBBBBB</option> 
<option value="3">CCCCCCCCC</option> 
<option value="4">DDDDDDDDD</option> 
</select> 
</span> 
<script type="text/javascript"> 
setReadOnly("span_select"); 
</script> 
<!-- 直接设置下拉框只读 --> 
<select onbeforeactivate="return false" onfocus="this.blur()" onmouseover="this.setCapture()" onmouseout="this.releaseCapture()"> 
</BODY> 
</HTML>

asp.net&nbsp后端C#代码

this.ddlSysCategory.Attributes.Add("onfocus","this.blur();"); 
this.ddlSysCategory.Attributes.Add("onbeforeactivate","return false"); 
this.ddlSysCategory.Attributes.Add("onmouseover","this.setCapture()"); 
this.ddlSysCategory.Attributes.Add("onmouseout","this.releaseCapture()");