防止接下来抽的时候再次抽中该怎么办啊
<!DOCTYPE html>
<html>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>jquery随机抽奖</title>
<head>
<script type="text/javascript" src="jq/jquery-3.1.1.js"></script></script>
<script type="text/javascript">
$(function(){
var alldata = new Array("2.jpg","3.jpg","4.jpg","5.jpg");
var num = alldata.length - 1;
var start = $("#start");
var btn = $("#btn");
var show = $("#show");
var open = false;
function change(){
var randomVal = Math.round(Math.random() * num);
var prizeName = alldata[randomVal];
start.attr("src",prizeName);
}
function run(){
if(!open){
timer=setInterval(change,30);
btn.removeClass('start').addClass('stop').text('停止');
open = true;
}else{
clearInterval(timer);
show.animate({bottom:"50px"},300);
show.animate({bottom:"0px"},300);
btn.removeClass('stop').addClass('start').text('开始抽奖');
open = false;
}
}
btn.click(function(){run();})
})
</script>
<style>
body{ background:#fff;}
.wrap{ width:300px; margin:100px auto; font-family:"微软雅黑";border: 1px solid red; }
.show{ width:300px; height:300px; background-color:#ff3300; line-height:300px; text-align:center; color:#fff; font-size:28px; -moz-border-radius:150px; -webkit-border-radius:150px; border-radius:150px; background-image: -webkit-gradient(linear,0% 0%, 0% 100%, from(#FF9600), to(#F84000), color-stop(0.5,#fb6c00)); -moz-box-shadow:2px 2px 10px #BBBBBB; -webkit-box-shadow:2px 2px 10px #BBBBBB; box-shadow:2px 2px 10px #BBBBBB;overflow: hidden; position: relative;}
.btn a{ display:block; width:120px; height:50px; margin:30px auto; text-align:center; line-height:50px; text-decoration:none; color:#fff; -moz-border-radius:25px; -webkit-border-radius:25px; border-radius:25px;}
.btn a.start{ background:#80b600;}
.btn a.start:hover{ background:#75a700;}
.btn a.stop{ background:#00a2ff;}
.btn a.stop:hover{ background:#008bdb;}
</style>
</head>
<body>
<div class="wrap">
<div class="show" id="show"><img id="start" src="1.jpg"></div>
<div class="btn">
<a href="javascript:void(0)" class="start" id="btn">开始抽奖</a>
</div>
</div>
</body>
</html>
常山造纸农