Typescript : Find common objects from two array using Lambda function

Question

I am using Typescript for below problem. I want to search object not simple alphabetic or number in the list.

Below are the two arrays. I want to get common objects in separate list without using any third party library.

    firstArray = [
           {
               "id": 4,
               "name": "Tata"
           },
           {
               "id": 11,
               "name": "Maruti"
           },
           {
               "id": 14,
               "name": "Mahindra"
           }
        ]

        secondArray = [
           {
               "id": 4,
               "name": "Tata"
           },
           {
               "id": 11,
               "name": "Maruti"
           },
           {
               "id": 15,
               "name": "Hyundai"
           },
           {
               "id": 21,
               "name": "Honda"
           } 
        ]
        
// Get Common Elements
// I am getting blank array as output

        console.log(firstArray.filter(( make ) => secondArray.includes( make)));

Is there good function or way to find out commons element?

Unless you use types and have a question related to them it's a **Javascript** question. — Mörre, May 02 '18 at 12:58
@Mörre i was just trying out available options anyway I want to make this in typescript only. — Morez, May 02 '18 at 13:02
Possible duplicate of [javascript object array difference and intersection of elements](https://stackoverflow.com/questions/33356504/javascript-object-array-difference-and-intersection-of-elements) — Toodoo, May 02 '18 at 13:04

score 26 · Accepted Answer · answered May 02 '18 at 13:03

You can use array#filter with array#some. For each object in the first array, check if id and name exist in the other array.

const firstArray = [{ "id": 4, "name": "Tata" }, { "id": 11, "name": "Maruti" }, { "id": 14, "name": "Mahindra" } ], 
      secondArray = [{ "id": 4, "name": "Tata" }, { "id": 11, "name": "Maruti" }, { "id": 15, "name": "Hyundai" }, { "id": 21, "name": "Honda" } ],
      result = firstArray.filter(o => secondArray.some(({id,name}) => o.id === id && o.name === name));
console.log(result);

score 1 · Answer 2 · answered May 02 '18 at 13:02

1

For ES6, you can also try sets,

For demonstration,

const thirdArray = [...new Set([...firstArray ,...secondArray])];

answered May 02 '18 at 13:02

Mohib Wasay

311
2
13

4

purpose of the your code is different. It is union but without duplicates. I want to create new array with common objects from arrays – Morez May 02 '18 at 13:04
Just tested it but sadly it doesn't work – floprm Oct 05 '22 at 16:10

Rajesh kumar · Answer 3 · 2023-02-24T13:33:41.400

In case, someone is wishing that extra parameters of 2nd array should be merged into the first array then here is the code:

const firstArray = [{ "id": 4, "name": "Tata" }, { "id": 11, "name": "Maruti" }, { "id": 14, "name": "Mahindra" }]

const secondArray = [{ "id": 4, "name": "Tata", "new": 1, junk: "as" }, { "id": 11, "name": "Maruti", "new": 2, junk: "as1" }, { "id": 15, "name": "Hyundai", "new": 3, junk: "asdds" }, { "id": 21, "name": "Honda", junk: "asasd" }]

const newArr =[]
const result = firstArray.filter(o => secondArray.some((sitm) => o.id === sitm.id && newArr.push({
    new: sitm.id,
    //add more fields if needed
    ...o
})));

console.log("*** final result ***", newArr);

Note: result is the just the common part of both arrays and newArr is common part plus the attributes you need from second array.

Typescript : Find common objects from two array using Lambda function

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