How do I get the value of a key from a list of objects in Javascript?

Question

I have a list of objects in the following way:

obj = [ { a:[1,2,3] }, { b:[4,5,6] }, { c:[7,8,9] } ]

How do I get the correspoding array for a key using javascript?

Eg. For b, I would get [4,5,6]. I need a function where I can give the key as input and it returns me the corresponding array associated with it.

This is a strange and somewhat inconvenient data structure. Is there a reason you're using an array of separate objects each with a unique key name, instead of just a single object like obj = {a: [1,2,3], b: [4,5,6], c: [7,8,9]}? — Daniel Beck
– Daniel Beck, Commented Jul 25, 2019 at 20:04
Actually this is a return I get from an api call and the data comes in this format. — Adirtha1704
– Adirtha1704, Commented Jul 25, 2019 at 20:04
Possible duplicate of Find object by id in an array of JavaScript objects — str
– str, Commented Jul 25, 2019 at 20:06

Maheer Ali · Accepted Answer · 2019-07-25 20:04:42Z

2

You can use find() and Object.keys(). Compare the first element of keys array to the given key.

const arr = [ { a:[1,2,3] }, { b:[4,5,6] }, { c:[7,8,9] } ];
const getByKey = (arr,key) => (arr.find(x => Object.keys(x)[0] === key) || {})[key]

console.log(getByKey(arr,'b'))
console.log(getByKey(arr,'c'))
console.log(getByKey(arr,'something'))

answered Jul 25, 2019 at 20:04

Maheer Ali

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Code Maniac · Accepted Answer · 2019-07-25 20:05:03Z

0

You can use find and in

let obj = [ { a:[1,2,3] }, { b:[4,5,6] }, { c:[7,8,9] } ]

let findByKey = (arr,key) => {
  return (arr.find(ele=> key in ele ) || {})[key]
}

console.log(findByKey(obj,'b'))
console.log(findByKey(obj,'xyz'))

answered Jul 25, 2019 at 20:05

Code Maniac

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1 Comment

baao Over a year ago

That may cause unwanted sideeffects and false trues. stackoverflow.com/questions/455338/…

baao · Accepted Answer · 2019-07-25 20:09:07Z

0

You can use find and hasOwnProperty

const arr = [ { a:[1,2,3] }, { b:[4,5,6] }, { c:[7,8,9] } ];

const byKey = (arr, key) => {
    return (arr.find(e => e.hasOwnProperty(key)) || {})[key];
};

console.log(byKey(arr, 'a'));

answered Jul 25, 2019 at 20:09

baao

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Comments

dezfowler · Accepted Answer · 2019-07-25 20:05:45Z

-1

Just use a property indexer i.e. obj['b']

answered Jul 25, 2019 at 20:05

dezfowler

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