How to extract value of nested object array?

Question

I'm trying to extract all links IDs of the object array shown below. This is how I was trying to get that:

const linkIDs = array
  .filter(d => d.links)
  .map(d => d.links)

But this gives me a nested array, which is not what I wanted.

[
  {
    "id: "1",
    "links": [
        {
            "id" : "Dn59y87PGhkJXpaiZ",
            "type" : "article"
        },
      {
            "id" : "PGhkJXDn59y87paiZ",
            "type" : "article"
        }
    ]
  },
  {
    "id: "2",
    "links": [
        {
            "id" : "GhkJXpaiZDn59y87P",
            "type" : "article"
        }
    ]
  },
  {
    "id": "3"
  }
]

So in this example I need the result

[ "Dn59y87PGhkJXpaiZ", "PGhkJXDn59y87paiZ", "GhkJXpaiZDn59y87P" ]

Answer 1

You can do like bellow, without using any other library.

var data = [
  {
    "id": "1",
    "links": [
        {
            "id" : "Dn59y87PGhkJXpaiZ",
            "type" : "article"
        },
       {
            "id" : "PGhkJXDn59y87paiZ",
            "type" : "article"
        }
    ]
  },
  {
    "id": "2",
    "links": [
        {
            "id" : "GhkJXpaiZDn59y87P",
            "type" : "article"
        }
    ]
  },
  {
    "id": "3"
  }
];

var result = data.filter(e => e.links)
                 .map(e => e.links.map(link => link.id))
                 .reduce((a, b) => a.concat(b), []);
                
console.log(result);