Return all nested objects with specific keys

Question

I have an array of objects in Javascript:

[
{a: 1, b: 2, c: 4},
{d: 10, a: 9, r: 2},
{c: 5, e: 2, j: 41}
]

I would like to return an array of all the objects that have the key name c by using the key name for the lookup.

What is the best way to accomplish this?

Iterate the array and check, if the object has the key. If it does, add it to the new array. — Geshode, Aug 02 '22 at 01:31
@Geshode it might be best to make use of inherent array methods such as `filter()` for something like this. — dqhendricks, Aug 02 '22 at 01:37
@dqhendricks I was just trying to nudge OP into a direction, so that they can start to do the work themself, instead of me writing the code for them. — Geshode, Aug 02 '22 at 02:41

score 2 · Accepted Answer · answered Aug 02 '22 at 09:16

2

You can use filter method and hasOwnProperty

const arr = [{a: 1, b: 2, c: 4},{d: 10, a: 9, r: 2},{c: 5, e: 2, j: 41}];
const myArray = array.filter(e => e.hasOwnProperty('c'))

answered Aug 02 '22 at 09:16

vitaretnama

126
3

score 1 · Answer 2 · edited Aug 02 '22 at 14:49

1

.filter + in operator

var arr = [
    {a: 1, b: 2, c: 4},
    {d: 10, a: 9, r: 2},
    {c: 5, e: 2, j: 41}
];
var result = arr.filter((x) => 'c' in x);
console.log(result)

edited Aug 02 '22 at 14:49

General Grievance

4,555
31
31
45

answered Aug 02 '22 at 05:09

Jay Patel

231
1
4

dqhendricks · Answer 3 · 2022-08-02T03:48:46.500

0

use filter(), and maybe hasOwnProperty() or another way to check if the property is present on the object.

const myarray = [
    { a: 1, b: 2, c: 4 },
    { d: 10, a: 9, r: 2 },
    { c: 5, e: 2, j: 41 }
];

const processedarray = myarray.filter( item => item.hasOwnProperty( 'c' ) );

console.log( processedarray );

edited Aug 02 '22 at 03:48

answered Aug 02 '22 at 01:36

dqhendricks

19,030
11
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83

Ian · Answer 4 · 2022-08-02T01:55:57.647

Try using filter and hasOwnProperty.

const data = [{
    a: 1, b: 2, c: 4
  },
  {
    d: 10, a: 9, r: 2
  },
  {
    c: 5,  e: 2, j: 41
  }
];

const filtered = (arr, prop) =>
  arr.filter(a => a.hasOwnProperty(prop));
  
console.log(
  JSON.stringify(filtered(data, 'c'))
);

If you want to return an array of objects with multiple specific keys, you can combine it with some.

const data = [{
    a: 1, b: 2, c: 4
  },
  {
    d: 10, a: 9, r: 2
  },
  {
    c: 5,  e: 2, j: 41
  }
];
  
const filtered = (arr, ...props) =>
  arr.filter(a => props.some(prop => a.hasOwnProperty(prop)));

console.log(
  JSON.stringify(filtered(data, 'b', 'j'))
);

Rawand · Answer 5 · 2022-08-02T14:24:54.087

0

the easiest way is to loop through the array to check if the object has a key named c

var arr = [
    { a: 1, b: 2, c: 4 },
    { d: 10, a: 9, r: 2 },
    { c: 5, e: 2, j: 41 }
]

// they both do the same job
var result = arr.filter(item => Object.keys(item).some(key => key === 'c'))
var filtered = arr.filter(item => item.hasOwnProperty('c'))


console.log(result);
console.log(filtered);

edited Aug 02 '22 at 14:24

answered Aug 02 '22 at 01:39

Rawand

377
3
11

`.some(key => key.indexOf('c') > -1)` will be true for keys *containing* the letter 'c'. I think you want `.some(key => key === 'c')` – danh Aug 02 '22 at 02:05
you are right, but i guess he got the idea, I will change the answer @danh – Rawand Aug 02 '22 at 14:23

score 0 · Answer 6 · answered Aug 02 '22 at 06:45

You can simply achieve this by using Array.filter() method along with Object.hasOwn().

Live Demo :

const arr = [
{a: 1, b: 2, c: 4},
{d: 10, a: 9, r: 2},
{c: 5, e: 2, j: 41}
];

const res = arr.filter(obj => Object.hasOwn(obj, 'c'));

console.log(res);

score -1 · Answer 7 · answered Aug 02 '22 at 01:40

This is My answer. Thank you

const arr = [
  {a: 1, b: 2, c: 4},
  {d: 10, a: 9, r: 2},
  {c: 5, e: 2, j: 41}
]

const filter = (arr, byKey) => {
  return arr.filter((ob) => {
    return Object.keys(ob).includes(byKey)
  })
}

console.log(filter(arr, 'c'))

Return all nested objects with specific keys

7 Answers7