//随机数函数 function rnd() { rnd.seed = (rnd.seed*9301+49297) % 233280; return rnd.seed/(233280.0); }; rnd.today=new Date(); rnd.seed=rnd.today.getTime(); function rand(number) { return Math.ceil(rnd()*number); }; //测试 var r = [0,0,0,0]; for(var i=0; i<1000000; i++) { var n = rand(3); ++r[n]; } document.write(r[1]+'<br/>'); document.write(r[2]+'<br/>'); document.write(r[3]+'<br/>');