JS(ES6):根据嵌套数组属性过滤数组 [英] JS (ES6): Filter array based on nested array attributes

问题描述

我有一个数组，看起来像这样:

I have an array, which looks like this:

const persons = [
  {
    name: "Joe",
    animals: [
      {species: "dog", name: "Bolt"},
      {species: "cat", name: "Billy"},
    ]
  },
  {
    name: "Bob",
    animals: [
      {species: "dog", name: "Snoopy"}
    ]
  }
];

现在我要根据物种进行过滤. 例如:每个有猫的人都应返回:

Now I want to filter based on the species. For example: every person which has a cat, should be returned:

const result = [
  {
    name: "Joe",
    animals: [
      {species: "dog", name: "Bolt"},
      {species: "cat", name: "Billy"},
    ]
  }
];

我已经尝试过使用filter()方法，如下所示:

I have tried with the the filter() method like this:

const result = persons.filter(p => p.animals.filter(s => s.species === 'cat'))

但这不会返回期望的结果(返回两个人).

But this doesn't return the desired result (it returns both persons).

如何基于嵌套数组的属性过滤数组?

How can I filter the array bases on an attribute of a nested array?

推荐答案

您的内部过滤器仍然为狗狗返回真实"值(空数组).添加.length，以使任何结果都不会成为0("falsey")

Your inner filter still returns a "truthy" value (empty array) for the dog person. Add .length so that no results becomes 0 ("falsey")

const result = persons.filter(p => p.animals.filter(s => s.species === 'cat').length)

对于每个注释和其他几个答案，由于目标是从内部循环中获取真实值，因此.some会更好地完成工作，因为如果有的话直接返回true项目匹配.

Per comments and several other answers, since the goal is to get a truthy value from the inner loop, .some would get the job done even better because it directly returns true if any items match.

const result = persons.filter(p => p.animals.some(s => s.species === 'cat'))

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