如何在 JavaScript 中解构数组数组？

Question

I have an array of arrays. Each nested array contain objects, however it may contain array of objects. For example:

let arr=[[{a:1}],[{b:2}, [{c:3}, {d:4}]]]

I want to create an array which will contain only the objects destructuring all the arrays. I tried

arr.reduce((a,b) => [...a,...b], [])

but what am I getting is :

[{a:1}, {b:2}, [{c:3},{d:4}]]

which is not what I want. I want to get:

 [{a:1}, {b:2}, {c:3}, {d:4}]   

Answer 1

You should consider using the Array.flat() method.

 console.log( [[{a:1}],[{b:2}, [{c:3}, {d:4}]]].flat() )

You'll notice the above example only flattens one level. This is because the depth parameter defaults to 1 . In our case, we need to flatten 2 levels, so we explicitly pass 2 to .flat() .

 console.log( [[{a:1}],[{b:2}, [{c:3}, {d:4}]]].flat(2) )

If you need it to go deeper still, you can increase this number. If you need it to handle any depth, use Infinity .

 console.log( [[{a:1}],[{b:2}, [{c:3}, {d:4}]]].flat(Infinity) )

It is worth noting that as of the writing of this answer, flat() is not supported by all browsers . However, most transpilers (such as Babel) will polyfill it and NodeJS 11+ supports it. The MDN documentation for Array.flat() has alternatives that use vanilla Javascript .