js 实现按权重随机抽奖

请实现抽奖函数rand，保证随机性
输入为表示对象数组，对象有属性n表示人名，w表示权重
随机返回一个中奖人名，中奖概率和w成正比

let peoples = [
  { n: 'p1', w: 1 },
  { n: 'p2', w: 100 },
  { n: 'p3', w: 100 }
];
let rand = function (p) {
  const totalWeight = p.reduce(function (pre, cur, index) {
    cur.startW = pre;
    return cur.endW = pre + cur.w
  }, 0)
  let random = Math.ceil(Math.random() * totalWeight)
  let selectPeople = p.find(people => people.startW < random && people.endW > random)
  return selectPeople.n
};