Typescript Select Ids from object

Question

I am new to Typescript. I want to select ids from observable

This is my observable

let myObj = [{
  "id": 1,
  "text": "Mary"
}, {
  "id": 2,
  "text": "Nancy"
}, {
  "id": 3,
  "text": "Paul"
}, {
  "id": 4,
  "text": "Cheryl"
}, {
  "id": 5,
  "text": "Frances"
}]

Expected Result :

let selectedIds = [1,2,3,4,5];

Can I do this without creating an array and pushing the ids in a for loop.

Try this http://stackoverflow.com/questions/19590865/from-an-array-of-objects-extract-value-of-a-property-as-array — Jonathan Smith, Dec 17 '16 at 10:20
Also you *start* with an array. `myObj.map(thing => thing.id)` would suffice. — jonrsharpe, Dec 17 '16 at 10:22
Yes **map** will do the things thanks Jonathan and jonrshare — Sathya V, Dec 17 '16 at 10:24

score 76 · Accepted Answer · answered Dec 17 '16 at 10:23

76

Use Array#map to map one array to another:

const myObj = [{"id":1,"text":"Mary"},{"id":2,"text":"Nancy"},{"id":3,"text":"Paul"},{"id":4,"text":"Cheryl"},{"id":5,"text":"Frances"}];

const selectedIds = myObj.map(({ id }) => id);

console.log(selectedIds);

answered Dec 17 '16 at 10:23

Ori Drori

183,571
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7

We can make type script like too "myObj.map(p=>p.id)" – Rajeev Sep 21 '20 at 08:27

score -8 · Answer 2 · edited Dec 17 '16 at 13:40

-8

<script>
      ..........Your Ajax / JSON  Request Sending Code

      function success(response)
      {
            var arr = JSON.parse(response);

            var selectedIds  = new Array();

            for(var i=0;i < arr.length ; i++)
            {
                  selectedIds["[" + arr[i].id + "]"] ; 
            }
            document.write(selectedIds);
      }

</script>

edited Dec 17 '16 at 13:40

Martijn Pieters

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answered Dec 17 '16 at 10:29

Ahsan Chishti

1

1

Try and provide an explanation along with the code snippet. It helps us understand your reasoning behind including the snippet. Additionally, the OP is specifically asking for a method of achieving this without looping through each item in the Array. – rootr Dec 14 '19 at 05:43

Typescript Select Ids from object

2 Answers2

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