Typescript Select Ids from object [duplicate]

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.

Also you start with an array. myObj.map(thing => thing.id) would suffice. — jonrsharpe
– jonrsharpe, Commented Dec 17, 2016 at 10:22
Yes map will do the things thanks Jonathan and jonrshare — Sathya V
– Sathya V, Commented Dec 17, 2016 at 10:24

Ori Drori · Accepted Answer · 2016-12-17 10:23:20Z

86

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, 2016 at 10:23

Ori Drori

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1 Comment

Rajeev Over a year ago

We can make type script like too "myObj.map(p=>p.id)"

Martijn Pieters · Accepted Answer · 2016-12-17 13:40:41Z

-9

<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, 2016 at 13:40

Martijn Pieters

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answered Dec 17, 2016 at 10:29

Ahsan Chishti

1

1 Comment

rootr Over a year ago

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.

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