<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title></title>
<script type="text/javascript">
window.onload = function () {
// 按钮不可用, 禁用
document.getElementById('btnLogin').disabled=true;
//// 按钮可用, 启用
//document.getElementById('btnLogin').disabled=false;
}
</script>
</head>
<body>
<input type="button" id="btnLogin" value="登录"/>
</body>
</html>