将内部数组从地图合并为一个的干净方法是什么？

Question

我目前有以下内容，如果没有forEach，有没有更简洁的方法？

今天是星期五，今天我的头都晕了:)

let productsObject = [{
  id: 1,
  addons: [{
    id: 1,
    group_id: 1
  }, {
    id: 2,
    group_id: 1
  }, {
    id: 3,
    group_id: 1
  }]
}, {
  id: 2,
  addons: [{
    id: 1,
    group_id: 2
  }, {
    id: 3,
    group_id: 2
  }]
}];

let addonsList = [];

productsObject.map(e => e.addons).forEach(e => { 
  addonsList = [...addonsList, ...e];
});

console.log(addonsList);

Answer 1

您可以将Array.prototype.reduce() 用于单线解决方案：

let productsObject = [{
  id: 1,
  addons: [{
    id: 1,
    group_id: 1
  }, {
    id: 2,
    group_id: 1
  }, {
    id: 3,
    group_id: 1
  }]
}, {
  id: 2,
  addons: [{
    id: 1,
    group_id: 2
  }, {
    id: 3,
    group_id: 2
  }]
}];

const addonsList = productsObject.reduce((acc, { addons }) => [...acc, ...addons], []);

console.log(addonsList);

Answer 2

另一个不错的选择是使用flatMap。顾名思义，它是flat 和map 方法的组合。

let productsObject = [{
  id: 1,
  addons: [{
    id: 1,
    group_id: 1
  }, {
    id: 2,
    group_id: 1
  }, {
    id: 3,
    group_id: 1
  }]
}, {
  id: 2,
  addons: [{
    id: 1,
    group_id: 2
  }, {
    id: 3,
    group_id: 2
  }]
}];

let addonsList = productsObject.flatMap(e => e.addons);

console.log(addonsList);