form表單提交後loading提示，以及提交一次後失效，避免重複提交

<form action="user/PPPOE" name="pppoeForm"
			onsubmit="return CheckPost();">
			<span>&nbsp;&nbsp;&nbsp;數據口：</span> <select name="Access">
				<c:forEach var="dc" items="${dataNc}">
					<option value="${dc.name}">${dc.name}</option>
				</c:forEach>
			</select> <br /> <br /> <span>&nbsp;&nbsp;&nbsp;用戶名:&nbsp;&nbsp;&nbsp;&nbsp;</span><input
				type="text" name="name" required="required"><br /> <br />
			<span>&nbsp;&nbsp;&nbsp;密碼:&nbsp;&nbsp;&nbsp;&nbsp;</span><input
				type="password" name="pwd" required="required"><br /> <br />
			&nbsp;&nbsp;&nbsp;<input type="submit" name="submit" value="確定" />
		</form>

<div id="showResult"
		style="color: #33CC70; position: absolute; top: 80px; left: 20em;">
	</div>

js

<script language="javascript">
   var submitcount=0;
   function CheckPost ()
   {
	   if (submitcount == 0){
		   $("#showResult").append("<div><img src='../admin/img/abc.gif' /><div>");   
		   submitcount++;
		   return true;
	   }else{
		   alert("正在操作，請不要重複提交，謝謝！");
	 　　　　　　return false;
	   }
   }
</script>

效果圖：

gif圖