不使用Math.random实现随机数。

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