js控制随机数生成概率代码实例

'use strict';
export default class GL {
  /
    构造函数
    @param {object} opt
    @param {number} opt.min 最小整数值
    @param {number} opt.max 最大整数值
    @param {Map} opt.fenpei 自定义概率 
   /
  constructor({ min, max, fenpei = new Map() }) {
    this.min = min;
    this.max = max;
    this.fenpei = fenpei;
  }

  /
    可分配百分比
   /
  get baifenbi() {
    return (1 - this.peizhi) / (this.max - this.min - this.fenpei.size);
  }

  /
    配置
   /
  get peizhi() {
    let result = 0;
    for (let i of this.fenpei.values()) {
      if (this.min <= i && i < this.max) result += i;
    }
    return result;
  }


  /
    随机数
    @returns {number} [min,max)
   /
  random() {
    let t = 0, r = Math.random();
    for (let i = this.min; i < this.max; i++) {
      this.fenpei.has(i) ? t += this.fenpei.get(i) : t += this.baifenbi;
      if (t > r) return i;
    }
    return null;
  }
}


let d = new GL({
  min: 0,
  max: 8,
  fenpei: new Map([
    [0, 0.5], // 数值，百分比
    [22, 0.4]
  ])
});

// 测试
let count = Array(10).fill(0);
for (let i = 0; i < 10000; i++) {
  count[d.random()] += 1;

}

for (let i = 0; i < count.length; i++) {
  console.log(count[i] / 10000);
}