计算布尔值数组中真实成员的数量 [英] Count the number of true members in an array of boolean values

问题描述

JavaScript的新手，我无法计算布尔值数组中的true数.我正在尝试使用reduce()函数.有人可以告诉我我在做什么错吗?

New to javascript and I'm having trouble counting the number of trues in an array of boolean values. I'm trying to use the reduce() function. Can someone tell me what I'm doing wrong?

   //trying to count the number of true in an array
    myCount = [false,false,true,false,true].reduce(function(a,b){
      return b?a++:a;
    },0);
    alert("myCount ="+ myCount);  // this is always 0

推荐答案

似乎您的问题已经解决，但是有很多更简单的方法可以解决.

Seems like your problem is solved already, but there are plenty of easier methods to do it.

Array.prototype.filter() -我认为最简单的一种.

Array.prototype.filter() - the easiest one, in my opinion.

console.log([true,false,true,false,true].filter(v => v).length);

甚至更简单:

console.log([true,false,true,false,true].filter(Boolean).length);

Array.prototype.forEach()

Array.prototype.forEach()

var myCounter = 0;

[true,false,true,false,true].forEach(v => v ? myCounter++ : v);

console.log(myCounter);

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