Compare two array of objects and filter element not present in second array

Question

Suppose I have two array of object as:

const array1 = [
  { name: 'detail1', title: 'detail1' },
  { name: 'detail2 ', title: 'detail2 ' },
  { name: 'detail3', title: 'detail3' },
  { name: 'detail4', title: 'detail4' },
  { name: 'detail5', title: 'detail5' },
  { name: 'detail6', title: 'detail6' },
  { name: 'detail7', title: 'detail7' }
]

const array2 = [
  { name: 'detail1', title: 'detail1' },
  { name: 'detail2 ', title: 'detail2 ' },
  { name: 'detail3', title: 'detail3' },
  { name: 'detail4', title: 'detail4' },
]

I want to compare two arrays i.e. array1 and array2 and get the missing element of aaray2.

For this I tried as:

var absent = array2.filter(e=>!array1.includes(e));

But I am unable to get missing element of array2.

My expected O/P :

          [ { name: 'detail5', title: 'detail5' },
            { name: 'detail6', title: 'detail6' },
            { name: 'detail7', title: 'detail7' }]

These are all the elements which are not present in array2.

What exactly am I doing wrong here?

Please let me know if anyone needs any further information.

you have different objects. only objects with same object reference is equal. — Nina Scholz
– Nina Scholz, Commented Jun 15, 2021 at 8:14
@NinaScholz So how exactly can I compare two array of objects? I couldn't find anything related to this. — Siva Pradhan
– Siva Pradhan, Commented Jun 15, 2021 at 8:19
Does this answer your question? How to get the difference between two arrays of objects in JavaScript — Bladeski
– Bladeski, Commented Jun 15, 2021 at 8:40
When are two objects considered equal in your scenario? Do all the key/value-pairs of an object have to be equal? Or is a comparison based on the name and/or title of an object enough? — 3limin4t0r
– 3limin4t0r, Commented Jun 15, 2021 at 10:06
@Bladeski Thank you for the suggestion. It guided me to exactly what I wanted. — Siva Pradhan
– Siva Pradhan, Commented Jun 15, 2021 at 11:49

Nina Scholz · Accepted Answer · 2021-06-15 09:07:58Z

2

You could build a normalised object with key and values and filter the objects.

const
    array1 = [{ name: 'detail1', title: 'detail1' }, { name: 'detail2 ', title: 'detail2 ' }, { name: 'detail3', title: 'detail3' }, { name: 'detail4', title: 'detail4' }, { name: 'detail5', title: 'detail6' }, { name: 'detail7', title: 'detail7' }, { name: 'detail8', title: 'detail8' }],
    array2 = [{ name: 'detail1', title: 'detail1' }, { name: 'detail2 ', title: 'detail2 ' }, { name: 'detail3', title: 'detail3' }, { name: 'detail4', title: 'detail4' }],
    sortEntriesByKey = ([a], [b]) => a.localeCompare(b),
    filter = array2.reduce((r, o) => {
        Object
            .entries(o)
            .sort(sortEntriesByKey)
            .reduce((o, [k, v]) => (o[k] ??= {})[v] ??= {}, r);
        return r;
    }, {});
    absent = array1.filter((o) => {
        let f = filter;
        return !Object
            .entries(o)
            .sort(sortEntriesByKey)
            .every(([k, v]) => f = f[k]?.[v]);
    });

console.log(absent);

.as-console-wrapper { max-height: 100% !important; top: 0; }

edited Jun 15, 2021 at 9:07

answered Jun 15, 2021 at 8:39

Nina Scholz

388k26 gold badges367 silver badges417 bronze badges

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

2 Comments

Siva Pradhan Over a year ago

It gives all the element present in array2, I only want the element which are missing in array2 when comparing with array1

Siva Pradhan Over a year ago

Thank you for your solution. Exactly what I wanted. :)

Tushar Shahi · Accepted Answer · 2021-06-15 08:41:55Z

1

Edit: you want objects in A not in B. It is ideal to loop through A, find if the element exists in B. If yes, then do not include it.

In javacript object references are compared when you do "==" or "===" or other array search methods.

{} == {} will return false. You can check in your dev console.

In your case, you will have to check specific properties.

var absent = array1.filter(e=>{
  let findInd = array2.findIndex((a)=>{
    return (a.name == e.name && a.title == e.title);});
return (findInd == -1); });

In the inner findIndex, I am finding index based on a condition. In filter method, I am returning true only if that index is -1(not found).

edited Jun 15, 2021 at 8:41

answered Jun 15, 2021 at 8:22

Tushar Shahi

21.6k2 gold badges25 silver badges48 bronze badges

4 Comments

Siva Pradhan Over a year ago

Thank you for your response. But when I am applying your code, on console.log(absent), it's giving me empty array, instead of missing element.

Tushar Shahi Over a year ago

What is the response you expect in your answer?

Siva Pradhan Over a year ago

I have added the expected O/P. Please let me know if you need any further details.

Tushar Shahi Over a year ago

I have updated the answer based on your input.

Oleg Barabanov · Accepted Answer · 2022-09-03 04:02:32Z

0

This worked for me:

let cart = [{
    "id": "6304a51af5726921c0dadd64",
    "qty": 1
  },
  {
    "id": "8704a51af5726921c0dadd64",
    "qty": 1
  },
  {
    "id": "4704a51af5726921c0dadd64",
    "qty": 1
  }
]

let cartList = [{
    "id": "6304a51af5726921c0dadd64",
    "qty": 1
  },
  {
    "id": "9704a51af5726921c0dadd64",
    "qty": 1
  }
]


let test = cart.some((element) =>
  cartList.some((e) => element.id === e.id)
);
console.log(" if any single object matched:", test);

let test1 = cart.filter((element) =>
  cartList.some((e) => element.id === e.id)
);
console.log("display matching objects :", test1);

edited Sep 3, 2022 at 4:02

Oleg Barabanov

2,7622 gold badges12 silver badges21 bronze badges

answered Aug 30, 2022 at 14:59

DevS

1

Comments

Faruk · Accepted Answer · 2023-05-24 12:53:12Z

0

const array1 = [
  { name: 'detail1', title: 'detail1' },
  { name: 'detail2 ', title: 'detail2 ' },
  { name: 'detail3', title: 'detail3' },
  { name: 'detail4', title: 'detail4' },
  { name: 'detail5', title: 'detail5' },
  { name: 'detail6', title: 'detail6' },
  { name: 'detail7', title: 'detail7' }
]

const array2 = [
  { name: 'detail1', title: 'detail1' },
  { name: 'detail2 ', title: 'detail2 ' },
  { name: 'detail3', title: 'detail3' },
  { name: 'detail4', title: 'detail4' },
]
const thirdArray = array1.filter((elem) => {
       return !array2.some((ele) => {
       return elem.name === ele.name
         });
       });

answered May 24, 2023 at 12:53

Faruk

92 bronze badges

Collectives™ on Stack Overflow

Compare two array of objects and filter element not present in second array

4 Answers 4

2 Comments

4 Comments

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

2 Comments

4 Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related