<head>
<script language="javascript">
function checkValid(form)
{
document.getElementById("submitbutton").disabled=true;
return true;
}
</script>
</head>
<body>
<form action="" method="post" >
<input type="submit" value="提交" id="submitbutton" onclick="return checkValid(this)"/>
</form>
</body>
</html>