select多选 multiple的使用
<html>
<head>
<script type="text/javascript">
function showDiv(id){
document.getElementById("selectOption").style.display="block";
document.getElementById("selectOption").style.position="absolute";
document.getElementById("selectOption").style.top=document.getElementById(id).offsetTop+25;
document.getElementById("selectOption").style.left=document.getElementById(id).offsetLeft+20;
}
function selectM()
{
var obj = document.getElementById("mySelect");
alert(obj.selectedIndex);
}
function checkselect(objname){
o = document.getElementById(objname);
t = document.getElementById("output");
var intvalue="";
for(i=0;i<o.length;i++){
if(o.options[i].selected){
intvalue+=o.options[i].value+",";
}
}
t.value=intvalue.substr(0,intvalue.length-1);
alert(intvalue);
}
</script>
</head>
<body>
<form>
<div id="selectOption" style='100px;height:50px;z-index:100;border:1px solid #0099FF;background:#cccccc;display:none;'>
<select id="mySelect" multiple="multiple" size="4">
<option value='苹果'>苹果</option>
<option value='桃子'>桃子</option>
<option value='香蕉'>香蕉</option>
<option value='桔子'>桔子</option>
</select>
<input type="button" onclick="checkselect('mySelect')" value="checkselect">
</div>
选中的项目：<input type="text" name="output">
<input id="lalla" type="button" onclick="showDiv(this.id)" value="选择">
<br/>
</form>
<p>在您点击 “选择多个” 按钮之前，请尝试同一时候选取多个选项。在点击 “选择多个” 按钮之后，请再试一次。</p>
</form>
</body>
</html>