select选中事件

<!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>
    <title>无标题页</title>
    <script type="text/javascript">
    function showMessage()
    {
        if(document.getElementById("selectID").options[document.getElementById("selectID").selectedIndex].value==1)
        {
            alert("你好，你选择了第 1 个");
            document.getElementById("divMessage").innerText=document.getElementById("selectID").options[document.getElementById("selectID").selectedIndex].value;
        }
        else if(document.getElementById("selectID").options[document.getElementById("selectID").selectedIndex].value==2)
        {
            alert("你好，你选择了第 2 个");
            document.getElementById("divMessage").innerText=document.getElementById("selectID").options[document.getElementById("selectID").selectedIndex].value;
        }
        else if(document.getElementById("selectID").options[document.getElementById("selectID").selectedIndex].value==3)
        {
            alert("你好，你选择了第 3 个");
            document.getElementById("divMessage").innerText=document.getElementById("selectID").options[document.getElementById("selectID").selectedIndex].value;
        }
        else if(document.getElementById("selectID").options[document.getElementById("selectID").selectedIndex].value==4)
        {
            alert("你好，你选择了第 4 个");
            document.getElementById("divMessage").innerText=document.getElementById("selectID").options[document.getElementById("selectID").selectedIndex].value;
        }
    }
    </script>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
</head>
<body>
<select id="selectID" onchange="return showMessage()">
    <option value="0">-----请选择----</option>
    <option value="1">1</option>
    <option value="2">2</option>
    <option value="3">3</option>
    <option value="4">4</option>
</select>
    <div id="divMessage"></div>
</body>
</html>
无标题页