abtest分流随机链接方法（javascript）

代码如下
<!DOCTYPE HTML>
<html>
<head>
<script type="text/javascript" src="../jquery-1.7.1.min.js"></script>
</head>
<body>
<!-- <div style="200px;height100px;background-color:#ccc;color:red;">¶¹¸¯¸ÉËêµÄ·¨¹úµçÊÓ¸²¸Ç</div>
<script type="text/javascript" src="http://www.yirendai.com/posterpic/126.js"></script> -->
<!-- <select>
    <option>测试下拉</option>
    <option>测试下拉</option>
    <option>测试下拉</option>
</select>
<button>点击</button>
<script>
    $(function(){
        $('button').click(function(){
            $('select').trigger('click');
        });
    })
    $('select').click(function(){
        console.log(1);
    });
</script> -->
<button id="tourl">产生</button>
<p id="strinfo">
</p>
<script type="text/javascript">
var urlList = [
    'http://www.baidu.com',
    'http://www.sina.com',
    'http://www.163.com',
    'http://www.qq.com'
];
    var strinfo;
    var tourlEle = document.getElementById('tourl');
    strinfo = document.getElementById('strinfo');
    tourlEle.onclick=function(){
        var k = getToUrl(urlList,100000);
        
    }

function getToUrl (urlList, maxNum) {
    var resKey = 0;
    if (urlList.length <= 0) {
        resKey =  0;
    }
    maxNum = maxNum ? maxNum : 10000;
    var keyList = [];
    var resKey = 0;
    var step = Math.ceil(maxNum/urlList.length);
    var key = Math.ceil(Math.random()*maxNum);

    for (var i=0; i < urlList.length; i++) {
        keyList[i] = step*(i+1);
    }
    for (var i = 0; i < keyList.length; i++) {
        if (key <= keyList[i]) {
            resKey = i;
            break;
        }
    }
    return resKey;
}
</script>
</body>
</html>