TypeScript- Extract values from array in array

Question

I have an array like that :

[{
        "id": 1,
        "city": [{
                "name": "BERLIN",
            }
        ],
    }, {
        "id": 2,
        "city": [{
                "name": "PARIS",
            }
        ],
    }, {
        "id": 3,
        "city": [{
                "name": "LONDON",
            }, {
                "name": "EXETER",
            }
        ],
    }

And I would like extract the values below :

[
    {id: 1, city: {name: "BERLIN"}, 
    {id: 2, city: {name: "PARIS"},
    {id: 3, city: {name: "LONDON"},
    {id: 3, city: {name: "EXETER"} 
]

I tried with and two map but, I don't have the result expected.

Can you help me for this issue.

Thank you.

@RobbyCornelissen: sorry, mistake of me, I fixed – Heptagram Mar 15 '21 at 23:55 — Heptagram, Mar 15 '21 at 23:55

score 3 · Accepted Answer · answered Mar 15 '21 at 23:57

3

You can use flatMap() for this:

const a = [{
  "id": 1,
  "city": [{
    "name": "BERLIN",
  }],
}, {
  "id": 2,
  "city": [{
    "name": "PARIS",
  }],
}, {
  "id": 3,
  "city": [{
    "name": "LONDON",
  }, {
    "name": "EXETER",
  }],
}];

const result = a.flatMap(({id, city}) => city.map(c => ({id, city: c})));

console.log(result);

answered Mar 15 '21 at 23:57

Robby Cornelissen

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Sorry, but I don't have flatmap in my angular project... – Heptagram Mar 16 '21 at 00:02
See [here](https://stackoverflow.com/questions/53556409/typescript-flatmap-flat-flatten-doesnt-exist-on-type-any). – Robby Cornelissen Mar 16 '21 at 00:12

TypeScript- Extract values from array in array

1 Answers1