抽奖（转）
工作需要，所以做了个抽奖转盘的插件，当然这里只做最简单的演示。
机制说明：
1、通过定义lottery-unit来控制节点的个数及索引；
2、通过设置lottery.crcle来定义需要转动的基本次数，在这个次数内，定时器的时间间隔不断递减，知道某个具体的数值；
3、当外界设置了lottery.prize即中奖目标的索引后，检查当当前转动次数已经大于lottery.crcle，这个过程开始递减定时器的时间间隔，直到lottery.prize等于lottery.prize，这时候初始化所有参数。
在线演示：http://blog.cxycs.com/demos/lottery/
源码下载：http://blog.cxycs.com/demos/lottery.rar
HTML代码：
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>九宫格 抽奖转盘演示</title>
<style type="text/css">
#lottery{
width: 454px;
margin: 100px auto 0;
}
#lottery table td{
width: 150px;
height: 150px;
text-align: center;
vertical-align: middle;
#ccc;
font-size: 24px;
color: #333;
}
#lottery table td a{
width: 150px;
height: 150px;
line-height: 150px;
display: block;
text-decoration: none;
}
#lottery table td.active{
color: red;
background-color: yellow;
}
</style>
</head>
<body>
<div id="lottery">
<table>
<tr>
<td class="lottery-unit lottery-unit-0">1</td>
<td class="lottery-unit lottery-unit-1">2</td>
<td class="lottery-unit lottery-unit-2">3</td>
</tr>
<tr>
<td class="lottery-unit lottery-unit-7">8</td>
<td><a href="#">开始</a></td>
<td class="lottery-unit lottery-unit-3">4</td>
</tr>
<tr>
<td class="lottery-unit lottery-unit-6">7</td>
<td class="lottery-unit lottery-unit-5">6</td>
<td class="lottery-unit lottery-unit-4">5</td>
</tr>
</table>
</div>
</body>
</html>
JS代码：
<script type="text/javascript" src="jquery-1.8.3.min.js"></script>
<script type="text/javascript">
var lottery={
index:0, //当前转动到哪个位置
count:0, //总共有多少个位置
timer:0, //setTimeout的ID，用clearTimeout清除
speed:200, //初始转动速度
times:0, //转动次数
cycle:50, //转动基本次数：即至少需要转动多少次再进入抽奖环节
prize:-1, //中奖位置
init:function(id){
if ($("#"+id).find(".lottery-unit").length>0) {
$lottery = $("#"+id);
$units = $lottery.find(".lottery-unit");
this.obj = $lottery;
this.count = $units.length;
$lottery.find(".lottery-unit-"+this.index).addClass("active");
};
},
roll:function(){
var index = this.index;
var count = this.count;
var lottery = this.obj;
$(lottery).find(".lottery-unit-"+index).removeClass("active");
index += 1;
if (index>count-1) {
index = 0;
};
$(lottery).find(".lottery-unit-"+index).addClass("active");
this.index=index;
return false;
},
stop:function(index){
this.prize=index;
return false;
}
};
function roll(){
lottery.times += 1;
lottery.roll();
if (lottery.times > lottery.cycle+10 && lottery.prize==lottery.index) {
clearTimeout(lottery.timer);
lottery.prize=-1;
lottery.times=0;
click=false;
}else{
if (lottery.times<lottery.cycle) {
lottery.speed -= 10;
}else if(lottery.times==lottery.cycle) {
var index = Math.random()*(lottery.count)|0;
lottery.prize = index;
}else{
if (lottery.times > lottery.cycle+10 && ((lottery.prize==0 && lottery.index==7) || lottery.prize==lottery.index+1)) {
lottery.speed += 110;
}else{
lottery.speed += 20;
}
}
if (lottery.speed<40) {
lottery.speed=40;
};
//console.log(lottery.times+'^^^^^^'+lottery.speed+'^^^^^^^'+lottery.prize);
lottery.timer = setTimeout(roll,lottery.speed);
}
return false;
}
var click=false;
window.onload=function(){
lottery.init('lottery');
$("#lottery a").click(function(){
if (click) {
return false;
}else{
lottery.speed=100;
roll();
click=true;
return false;
}
});
};
</script>
来源：http://blog.cxycs.com/article/56
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