过滤后将数组合并为一个数组 [英] Merge arrays to one array after filtering

问题描述

我有对象数组，我只取位置数组.我的目标是将这些位置数组合并为一个数组，但是我没有这样做并得到空数组.我是这样做的:

I've got array of objects, where I take only locations array. My goal is to merge these locations array to one array, however I fail to do so and get empty array. This is how I do it:

let results = [{
    id: '1',
    locations: ['aaaa', 'bbbbbb', 'cccccc']
  },
  {
    id: '2',
    locations: []
  },
  {
    id: '3',
    locations: ['ddd', 'aaadsad', 'sefd']
  },
  {
    id: '4',
    locations: ['ffff', 'eeee', 'sfdsfsd']
  },
];
const locationIds = [].concat.apply([], ...results.filter(s => s.locations && s.locations.length > 0).map(({
  locations
}) => ({
  locations
})));

console.log(locationIds);

我在这里做错了什么?结果应该是['aaaa', 'bbbbbb', 'cccccc', 'ddd', 'aaadsad', 'sefd', 'ffff', 'eeee', 'sfdsfsd'];

what I am doing wrong here? The result should be ['aaaa', 'bbbbbb', 'cccccc', 'ddd', 'aaadsad', 'sefd', 'ffff', 'eeee', 'sfdsfsd'];

推荐答案

这里不需要 filter.只需通过传递一个 回调 提供的函数来使用 map 方法，该函数应用于数组中的每个项目.

You don't need filter here. Just use map method by passing a callback provided function which is applied for every item on the array.

let results = [{ id: '1', locations: ['aaaa', 'bbbbbb', 'cccccc'] }, { id: '2', locations: [] }, { id: '3', locations: ['ddd', 'aaadsad', 'sefd'] }, { id: '4', locations: ['ffff', 'eeee', 'sfdsfsd'] }, ];

const locationIds = [].concat(...results.map(s => s.locations));

console.log(locationIds);

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