输入框为空的时候按钮置灰不可点
<html>
<script language="JavaScript" type="text/javascript">
function changeBtnable(){
$("#btn").removeAttr("disabled");
}
function changeBtndisable(){
$("#btn").attr("disabled","true");
}
function checkInput(){
var text = $("#money").val();
if(text==null||text==""){
changeBtndisable();
}
}
</script>
<script src="jquery-3.1.1.min.js"></script>
<body>
<div id="dd">
<input id="money" onmouseleave="checkInput()" oninput="changeBtnable()"/>
<input id="btn" disabled type="button"/>
</div>
</body>