使用reduce方法创建2个数组

Question

我有一个对象数组。使用循环后的reduce方法我想接收两个单独的数组。现在，我正在这样做。

const dogs = [
  { weight: 22, curFood: 250, owners: ['Alice', 'Bob'] },
  { weight: 8, curFood: 200, owners: ['Matilda'] },
  { weight: 13, curFood: 275, owners: ['Sarah', 'John'] },
  { weight: 32, curFood: 340, owners: ['Michael'] },
];

所以，通过下面的reduce方法，我收到了我想要的结果（2个数组）。

const ownersEatTooMuch = dogs.reduce(function (acc, dog) {
  if (dog.curFood > dog.recommended * 1.1) {
    acc.push(dog.owners);
  }
  return acc.flat();
}, []);

const ownersEatTooLess = dogs.reduce(function (acc, dog) {
  if (dog.curFood < dog.recommended * 0.9) {
    acc.push(dog.owners);
  }
  return acc.flat();
}, []);

但是是否可以将其合并到一个reduce方法中以创建2个数组。我想象这样的情况，

const [ownersEatTooMuch1, ownersEatTooLess1] = dogs.reduce(function (dog) {
  // When the condition will be true i want to fill first array ownersEatTooMuch1 and when another condition will be true i want to fill second array ownersEatTooLess1
}, [[], []]);

const [ownersEatTooMuch1, ownersEatTooLess1] = dogs.reduce(
  function (dog) {
    if (dog.curFood > dog.recommended * 1.1) {
      acc.push(dog.owners);
    }
  },
  [[], []]
);

我只是不明白如何确定这些之间的[[]，[]，然后推入ownerEatTooMuch1或此处ownerEatTooLess1

Answer 1

我希望这就是您正在寻找的。 因为您的示例代码不起作用（

recommended

未定义），并且输出不清楚，所以我不确定这是否是您想要的。

根据您提供的代码，您想要 2 个“吃太多”或“吃太少”的数组。

那些既不“太多”也不“太少”的情况呢？ 请参阅我在数组定义中的评论：

does not apppear anywhere, neither "too much" or "too less"

const dogs = [
    { weight: 22, curFood: 250, owners: ['Alice', 'Bob'], recommended: 10 },
    { weight: 8, curFood: 200, owners: ['Matilda'], recommended: 2000 },
    { weight: 13, curFood: 275, owners: ['Sarah', 'John'], recommended: 300 }, // does not apppear anywhere, neither "too much" or "too less"
    { weight: 32, curFood: 340, owners: ['Michael'], recommended: 1000 },
];



const [ownersEatTooMuch, ownersEatTooLess] = dogs.reduce((arr, dog) => {
    
    if (dog.curFood > dog.recommended * 1.1) {
        arr[1].push(...dog.owners);
    }

    if (dog.curFood < dog.recommended * 0.9) {
        arr[0].push(...dog.owners);
    }

    return arr;

}, [
    [], // too much
    []  // too less
]);


console.log(ownersEatTooLess, ownersEatTooMuch)

reduce 迭代每次传递给它的初始数组都会返回，这是一个 2 层数组。

1. Item = 数组，用于“太多”的人，
2. Item = 人“太少”的数组。

然后根据您的计算填充这些数组。

reduce 返回的 2 层数组随后被解构为变量

ownersEatTooMuch

&

ownersEatTooLess

。