使用 array.map() 从对象数组中查找元素

Question

我有一个对象数组，我想返回所有ids 的数组。例如：

const arr = [
    {Locations:[{id:2129, Name: 'testAA'}, {id:3431, Name: 'testAB'}, {id:4373, Name: 'testAC'}]},
    {Locations:[{id:2545, Name: 'testBA'}, {id:3431, Name: 'testBB'}]}
];     

我想返回：[2129, 3431, 4373, 2545, 3431]

我尝试过以下操作：

arr.map((value) => {
    let newarray = [];
    return newarray += value['Locations'].map(ID => ID.id);
});

这将返回：["2129,3431,4373", "2545,3431"]

我如何组合这两个数组？

Answer 1

鉴于您的输入和输出不是一对一的映射，这似乎不是.map(). 相反，我会考虑.map()仅在内部数组上使用，但.reduce()在外部数组上使用。

const arr = [{Locations:[{id:2129, Name: 'testAA'}, {id:3431, Name: 'testAB'}, {id:4373, Name: 'testAC'}]},{Locations:[{id:2545, Name: 'testBA'}, {id:3431, Name: 'testBB'}]}];     

const result = arr.reduce((acc,{Locations}) => [...acc, ...Locations.map(i=>i.id)], []);

console.log(result);

作为替代方案，您可以使用.concat()：

const arr = [{Locations:[{id:2129, Name: 'testAA'}, {id:3431, Name: 'testAB'}, {id:4373, Name: 'testAC'}]},{Locations:[{id:2545, Name: 'testBA'}, {id:3431, Name: 'testBB'}]}];     

const result = arr.reduce((acc,{Locations}) => acc.concat(Locations.map(i=>i.id)), []);

console.log(result);