Filter Array From Another Array in ES6

Question

I need to filter out contacts from data. Whatever data gets from contacts should be filtered out in remainingData

contacts = [
    {
        "contact_id": 12,
        "f_name": "RARA",
    },
    {
        "contact_id": 14,
        "f_name": "BABA",
    },
    {
        "contact_id": 15,
        "f_name": "CACA",
    },
    {
        "contact_id": 14,
        "f_name": "DADA",
    },
]


data = [
    {
        "contact_id": 12,
        "f_name": "RARA",
    },
     {
        "contact_id": 14,
        "f_name": "DADA",
    },
]


remainingData = [
     {
        "contact_id": 14,
        "f_name": "BABA",
    },
    {
        "contact_id": 15,
        "f_name": "CACA",
    },
]

CODE

const remainingData = contacts.filter(item => item.contact_id !== data.contact_id)

This is the same as your [previous question](https://stackoverflow.com/questions/68609607/get-object-from-array-in-es6). — Ouroborus, Aug 01 '21 at 11:19
@Ouroborus. Its different. Its array of object vs array of objects — Joseph, Aug 01 '21 at 11:19
@Joseph see [Array.prototype.filter()](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/filter) and [Arrow function expressions](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/Arrow_functions) docs... — Lluser, Aug 01 '21 at 11:26

Nitheesh · Accepted Answer · 2021-08-01T11:35:09.903

Solution using array.filter

contacts = [
    { "contact_id": 12, "f_name": "RARA" },
    { "contact_id": 14, "f_name": "BABA" },
    { "contact_id": 15, "f_name": "CACA" },
    { "contact_id": 14, "f_name": "DADA" },
]


data = [ 
    { "contact_id": 12, "f_name": "RARA" },
    { "contact_id": 14, "f_name": "DADA" },
]

const remainingData = contacts.filter(item => !data.find((node) => item.contact_id === node.contact_id && item.f_name === node.f_name));

console.log(remainingData);

Alternative solution using array.reduce

contacts = [
    { "contact_id": 12, "f_name": "RARA" },
    { "contact_id": 14, "f_name": "BABA" },
    { "contact_id": 15, "f_name": "CACA" },
    { "contact_id": 14, "f_name": "DADA" },
]


data = [ 
    { "contact_id": 12, "f_name": "RARA" },
    { "contact_id": 14, "f_name": "DADA" },
]


const remainingData = contacts.reduce((acc, curr) => {
    const searchNode = data.find((node) => node.contact_id === curr.contact_id && node.f_name === curr.f_name);
    if(!searchNode) {
        acc.push(curr);
    }
    return acc;
}, []);

console.log(remainingData);

If you want the result of filtration back in the contacts variable just assign back the result of filtrarion to the same variable like

contacts = contacts.filter(item => !data.find((node) => item.contact_id === node.contact_id && item.f_name === node.f_name))

If you are performing `arrayfilter` or `array.reduce` just re assign the `contacts` variable with the response of filtration like `contacts = contacts.filter(item => !data.find((node) => item.contact_id === node.contact_id && item.f_name === node.f_name))` — Nitheesh, Aug 01 '21 at 11:32

score 0 · Answer 2 · answered Aug 01 '21 at 11:25

You can map your array of objects containing the ids to a normal array with only the ID's where you can check against

let contacts = [{
    "contact_id": 12,
    "f_name": "RARA",
  },
  {
    "contact_id": 14,
    "f_name": "BABA",
  },
  {
    "contact_id": 15,
    "f_name": "CACA",
  },
  {
    "contact_id": 14,
    "f_name": "DADA",
  },
]

let data = [{
    "contact_id": 12,
    "f_name": "RARA",
  },
  {
    "contact_id": 14,
    "f_name": "DADA",
  },
]

let filtered = contacts.filter(item => (data.map(x => (x.contact_id)).some(id => (id === item.contact_id))))

console.log(filtered)

Alwani Anis · Answer 3 · 2021-08-01T12:11:27.703

To compare two objects we need to compare unique field (if exist) , so if contact_id is unique:

const remainingData = contacts.filter(item => data.find((node) => item.contact_id === node.contact_id )=='undefined');

Otherwise we should compare the two objects after converting them to json string , so :

const remainingData = contacts.filter(item => data.find((node) => JSON.stringify(item) === JSON.stringify(node))=='undefined');

Filter Array From Another Array in ES6

3 Answers3