使用javascript random函数以概率形式返回值
如下列代码,50%的概率返回A,20%的概率返回B,30%的概率返回C
var d = Math.random();
if (d < 0.5)
// 50% chance of being here
return 'A';
else if (d < 0.7)
// 20% chance of being here
return 'B';
else
// 30% chance of being here
return 'C';