JavaScript: add new property to array elements according to another array

Question

I have two arrays.

When comparing, if arr1 property id matches with arr2 property id, then add new property tag: assign else add tag: ''

I have tried the below code:

var result = arr1.filter(({ id: id }) => 
  !arr2.some(({ name: name }) => name === id)
);

Sample inputs:

var arr1 = [
  {id:1, name: "ram"},
  {id:24, name: "zen"},
  {id: 3, name: "sam"}
]
var arr2 = [
  {id:24, name: "zen"},
  {id: 3, name: "sam"}
]

Expected Output:

 [
  {id:1, name: "ram", tag:''},
  {id:24, name: "zen", tag: 'yes'},
  {id: 3, name: "sam", tag: 'yes'}
]

The duplicate assigned is for merging arrays, not what OP is looking for. — Majed Badawi
– Majed Badawi, Commented Feb 12, 2022 at 15:14

Majed Badawi · Accepted Answer · 2022-02-12 15:04:20Z

-1

Create a Set of ids in arr2 using Array#map
Again, using Array#map, iterate over arr1 and set tag using Set#has

const 
  arr1 = [ {id:1, name: "ram"}, {id:24, name: "zen"}, {id: 3, name: "sam"} ],
  arr2 = [ {id:24, name: "zen"}, {id: 3, name: "sam"} ];
  
const arr2IdsSet = new Set( arr2.map(({ id }) => id) );

const res = arr1.map(e => ({ ...e, tag: arr2IdsSet.has(e.id) ? 'yes' : '' }));

console.log(res);

answered Feb 12, 2022 at 15:04

Majed Badawi

28.5k4 gold badges30 silver badges56 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

JavaScript: add new property to array elements according to another array

1 Answer 1

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related