var rand = (function(){  var today = new Date();   var seed = today.getTime();  function rnd(){    seed = ( seed * 9301 + 49297 ) % 233280;    return seed / ( 233280.0 );  };  return function rand(number){    return Math.ceil(rnd(seed) * number);  };})();console.log(rand(100))console.log(rand(100))console.log(rand(100))console.log(rand(100))console.log(rand(100))console.log(rand(100))console.log(rand(100))//原理参看这里 http://www.zhihu.com/question/22818104

不使用Math.random实现随机数。