Javascript For 循环和Reduce。它是否正确

Question

我是 JavaScript 新手，所以我一直在努力寻找方法来更多地了解它。我一直以两种方式创建代码。 For 循环和使用数组方法的高阶函数，例如reduce、map、filter 等。我将发布一个数组、一个reduce 代码和for 循环。谁能看出我的 for 循环是否正确？

var people = [
{ name: "Jesse", age: 32, gender: "male" },
{   name: "Tommi", age: 40, gender: "female" },
{   name: "John",   age: 19, gender: "male" },
{   name: "Toni",   age: 50, gender: "trans" },
{   name: "Gene",   age: 19, gender: "trans" },
{   name: "Freddy", age: 80, gender: "male" }

];

我知道这个方法是正确的

var reduceGenderSum = people.reduce(function(obj, person){
if(!obj[person.gender]){
    obj[person.gender] = 1;
} else {
    obj[person.gender] += 1;
}
return obj;
}, {})

但是我不太确定这种使用 for 循环的方式，但是有人可以帮我仔细检查一下吗？

function genderSumFn(){
var count = 0;
var count2 = 0;
var count3 = 0;
for(var i = 0; i < people.length; i ++){
    if(people[i].gender === 'male'){
        count ++;
    } else if(people[i].gender === 'female'){
        count2 ++
    } else {
        count3 ++
    }
}
return { male: count, female: count2, trans: count3 };
}

我得到相同的输出。我只是想确保我使用 for 循环正确地完成了它。

Answer 1

如果 for 循环的方法与 reduce 的回调中的方法几乎相同，您也可以使用对象。

function getGenderCount(people) {
    var count = {},
        i;

    for (i = 0; i < people.length; i++) {
        count[people[i].gender] = count[people[i].gender] || 0;
        count[people[i].gender]++;
    }
    return count;
}

var people = [{ name: "Jesse", age: 32, gender: "male" }, { name: "Tommi", age: 40, gender: "female" }, { name: "John", age: 19, gender: "male" }, { name: "Toni", age: 50, gender: "trans" }, { name: "Gene", age: 19, gender: "trans" }, { name: "Freddy", age: 80, gender: "male" }];

console.log(getGenderCount(people));