How to filter an objects attributes based on an attribute key?

Question

I have an object

> state
{ homeStreet1: 'a', homeStreet2: 'b', homeStreet3: 'c', State: 'MA' }

> Object.entries(state)
[
  [ 'homeStreet1', 'a' ],
  [ 'homeStreet2', 'b' ],
  [ 'homeStreet3', 'c' ],
  [ 'State', 'MA' ]
]

How can I create a new object from this object that filters out an attribute?

I can do

> Object.entries(state).filter(([key,value]) => { return key !== 'homeStreet3' })

which gives me

> [ [ 'homeStreet1', 'a' ], [ 'homeStreet2', 'b' ], [ 'State', 'MA' ] ]

as a new array with the values I want, but how to get that as an object?

[`Object.fromEntries`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/fromEntries) — VLAZ, Aug 18 '20 at 13:41
Does this answer your question? [How to create an object from an Array of key-value pairs?](https://stackoverflow.com/questions/20059995/how-to-create-an-object-from-an-array-of-key-value-pairs) — jonrsharpe, Aug 18 '20 at 14:20

score 3 · Answer 1 · edited Aug 18 '20 at 13:49

3

There are two ways that you could choose which fit yours the most

const arr = [
  ["homeStreet1", "a"],
  ["homeStreet2", "b"],
  ["State", "MA"],
]

const res1 = Object.fromEntries(arr)
const res2 = arr.reduce((acc, [key, value]) => ({ ...acc, [key]: value }), {})

console.log(res1)
console.log(res2)

edited Aug 18 '20 at 13:49

Nick Parsons

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answered Aug 18 '20 at 13:45

hgb123

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score 2 · Answer 2 · answered Aug 18 '20 at 13:52

The shortest approach is to take a destrcturing with a target for the unwanted property homeStreet3 and get the rest as result.

const
    state = { homeStreet1: 'a', homeStreet2: 'b', homeStreet3: 'c', State: 'MA' },
    { homeStreet3, ...result } = state;

console.log(result);

score 0 · Answer 3 · answered Aug 18 '20 at 14:13

Expanding on this answer:

const arr = [
  ["homeStreet1", "a"],
  ["homeStreet2", "b"],
  ["State", "MA"],
]

const res1 = Object.fromEntries(arr)
const res2 = arr.reduce((acc, [key, value]) => ({ ...acc, [key]: value }), {})

console.log(res1)
console.log(res2)

const filteredEntries = Object.entries(state).filter(([key]) => key !== 'homeStreet3')

// This
const newState = filteredEntries.reduce((acc, [key, value]) => ({ ...acc, [key]: value }), {})

// Or this
const newState = Object.fromEntries(filteredEntries);

How to filter an objects attributes based on an attribute key?

3 Answers3