<script type="text/javascript">
//加载完成的回调函数
window.onload = function () {
var btn1 = document.getElementById(\'btn1\');
btn1.onclick = function () {
alert(document.getElementById(\'username\').value)
}
}
</script>
<script type="text/javascript">
//页面加载完成回调
$(function () {
// 查找按钮的dom
// var btn2 = $(\'#btn2\');
$(\'#btn2\').click(function () {
alert($(\'#username\').val());
})
})
</script>