一个抽奖程序 要怎么把出现几率一等奖3%,二等奖7%,三等奖15%,未中奖75%的出现几率 <html>
<title>未命名</title>
<head>
<meta http-equiv=Content-Type content="text/html; charset=gb2312">
</head>
<body>
<SCRIPT LANGUAGE="JavaScript">
var alldata = "一等奖,二等奖,三等奖,未中奖"
var alldataarr = alldata.split(",")
var num = alldataarr.length-1
var timer
function change(){
document.getElementById("oknum").value = alldataarr[GetRnd(0,num)];
}
function start(){
clearInterval(timer);
timer = setInterval('change()',46);
}
function ok(){
clearInterval(timer);
}
function GetRnd(min,max){
return parseInt(Math.random()*(max-min+1));
}
</SCRIPT>
<input type="text" id="oknum" name="oknum" value="">
<button onclick="start()" accesskey="s">开始抽奖(<U>S</U>)</button>
<button onclick="ok()" accesskey="o">停止(<U>O</U>)</button>
</body>
</html>
<title>未命名</title>
<head>
<meta http-equiv=Content-Type content="text/html; charset=gb2312">
</head>
<body>
<SCRIPT LANGUAGE="JavaScript">
var alldata = "一等奖,二等奖,三等奖,未中奖"
var alldataarr = alldata.split(",")
var num = alldataarr.length-1
var timer
function change(){
document.getElementById("oknum").value = alldataarr[GetRnd(0,num)];
}
function start(){
clearInterval(timer);
timer = setInterval('change()',46);
}
function ok(){
clearInterval(timer);
}
function GetRnd(min,max){
return parseInt(Math.random()*(max-min+1));
}
</SCRIPT>
<input type="text" id="oknum" name="oknum" value="">
<button onclick="start()" accesskey="s">开始抽奖(<U>S</U>)</button>
<button onclick="ok()" accesskey="o">停止(<U>O</U>)</button>
</body>
</html>
parseInt(Math.random() * 100)if(<3){Lv1}elseif(<10){Lv2}elseif(<25){Lv3}else{LEVEL4}
其实几率都是一样的都用Math.random(),只是个数问题