CODEWITHSUNDEEP
javascriptnode.js
Siva Pradhan
Siva Pradhan

Reputation: 861

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

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.

Upvotes: 0

Views: 1976

Answers (4)

Faruk
Faruk

Reputation: 9

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
         });
       });

Upvotes: 0

DevS
DevS

Reputation: 1

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);

Upvotes: 0

Nina Scholz
Nina Scholz

Reputation: 386680

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; }

Upvotes: 2

Tushar Shahi
Tushar Shahi

Reputation: 20606

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).

Upvotes: 1

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