An explanation of JavaScript's implementation of randomly generating events based on probability

This article mainly introduces a detailed explanation of JavaScript's random generation of events based on probability, which has certain reference value. Interested friends can refer to it

Recently made a JavaScript random generation of events based on probability, so I sorted out my thoughts and wrote a small demo:

/*
*在抽奖的活动中经常会用到这个算法，不同奖项的获取概率不同，要按概率去随机生成对应的奖品
*
*/
function random(arr1, arr2) {
  var sum = 0,
    factor = 0,
    random = Math.random();

  for(var i = arr2.length - 1; i >= 0; i--) {
    sum += arr2[i]; // 统计概率总和
  };
  random *= sum; // 生成概率随机数
  for(var i = arr2.length - 1; i >= 0; i--) {
    factor += arr2[i];
    if(random <= factor) 
     return arr1[i];
  };
  return null;
};

// test
var a = [&#39;mac&#39;, &#39;iphone&#39;, &#39;vivo&#39;, &#39;OPPO&#39;];
var b = [0.1, 0.2, 0.3, 0.4];
console.log(random(a, b));

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