How can i get an object from an array of objects

Question

At the entrance I have such an array with objects. Function that converts an incoming array of objects into an object. Using the function, I need to bring it to this form.

var array = [ 
   { k1:v1 },
   { k2:v2 },
   { k3:v3 }
];

function arrayToObject(array) { return object }

var object = { 
    v1: k1,
    v2: k2,
    v3: k3, 
}

There are so many answers out there that can help: https://stackoverflow.com/questions/19590865/from-an-array-of-objects-extract-value-of-a-property-as-array for example — mplungjan, Feb 02 '19 at 15:21

Nina Scholz · Answer 1 · 2019-02-02T15:19:10.933

2

You could taske Object.assign and spread the reversed objects.

var array = [ { k1: 'v1' }, { k2: 'v2' }, { k3: 'v3' }],

object = Object.assign(...array.map(o => Object
    .entries(o)
    .reduce((r, [k, v]) => Object.assign(r, { [v] : k }), {})
));

console.log(object);

edited Feb 02 '19 at 15:19

answered Feb 02 '19 at 15:15

Nina Scholz

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He wants the keys reversed, apparently (might be a mistake however...). Edit: note that I didn't downvote the answer though! – Jeto Feb 02 '19 at 15:16
The keys of the returned object must be the values of the elements of the original array – Илия Полторацкий Feb 02 '19 at 15:25
@ИлияПолторацкий, it should do it now. – Nina Scholz Feb 02 '19 at 15:43
But why the complexity? Because you can? Have a look at my answer for something simple and readable – mplungjan Feb 02 '19 at 16:05

score 1 · Accepted Answer · answered Feb 02 '19 at 15:16

1

Use forEach loop

var array = [ 
   { k1:'v1' },
   { k2:'v2' },
   { k3:'v3' }
]

function a()
{
var obj={};
array.forEach((e)=>obj[e[Object.keys(e)[0]]]=Object.keys(e)[0])
console.log(obj)
}
a();

answered Feb 02 '19 at 15:16

ellipsis

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Could you explain this piece of code? @AshayMandwarya – Илия Полторацкий Feb 03 '19 at 21:21
The forEach loop is used to itearte over an array one by one. the e on every iteration represents the object in the array. `Object.keys(e)[0]` this gives us an array of all the keys of the object e. There is only one so we use [0] to get that key. We access the value corresponding to that key using e[key] we get the key from the above `Object.keys(e)[0]` accessing this gives us the value corresponding to that key. Now we have the value, inside the empty object `obj` we make this as the key again using [] `obj[key]` and this key is given the value of `Object.keys(e)[0]` which is the key itself – ellipsis Feb 03 '19 at 21:35
Thus interchanging the key and value. Hope you understood – ellipsis Feb 03 '19 at 21:35
T u so much @AshayMandwarya – Илия Полторацкий Feb 03 '19 at 22:43

score 1 · Answer 3 · answered Feb 02 '19 at 15:17

You can use Object.entries() and .reduce() methods to get the desired output:

const array = [ 
   { k1:'v1' },
   { k2:'v2' },
   { k3:'v3' }
];

const obj = Object.entries(
    array.reduce((r, c) => Object.assign(r, c), {})
).reduce((r, [k, v]) => (r[v] = k, r), {});

console.log(obj);

score 1 · Answer 4 · answered Feb 02 '19 at 15:17

1

Array.reduce and use Object.keys over each array element.

var array = [ 
   { k1: 'v1' },
   { k2: 'v2' },
   { k3: 'v3' }
]

var obj = array.reduce((obj, item) => {
  Object.keys(item).forEach(key => obj[item[key]] = key)
   
  return obj
}, {})

console.log(obj)

answered Feb 02 '19 at 15:17

nicholaswmin

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You mean using a `forEach`? – nicholaswmin Feb 02 '19 at 15:59
We've had that conversation before. I don't like your approach. I like my transformations to be done in one-go. – nicholaswmin Feb 02 '19 at 16:02
1

It's not an insult. I really think you're confused as to what side-effect means. – nicholaswmin Feb 02 '19 at 16:08
Sorry but I still think you're confused as to what side-effect means. Your example modifies a variable outside its local environment which is the very definition of a side-effect. I don't agree on `noobs do not need clever` either. They can click the links I gave them and learn about `reduce`, which is how I learned about it as well. – nicholaswmin Feb 02 '19 at 16:14
Ok let's agree to disagree, which for the record I do disagree with all your points. – nicholaswmin Feb 02 '19 at 16:26
Yeah trust me, I would hate that as well. – nicholaswmin Feb 02 '19 at 16:27

score 0 · Answer 5 · answered Feb 02 '19 at 16:49

0

And another one:

 const result = {};

 for(const [[key, value]] of array.map(Object.entries))
   result[value] = key;

answered Feb 02 '19 at 16:49

Jonas Wilms

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mplungjan · Answer 6 · 2019-02-02T16:31:06.120

-1

I am not sure why the other answers go through hoops to make this as clever as possible.

I find this more readable. I am not using reduce because I find the word misleading. A simple forEach makes more sense to me

const array = [ 
   { k1:'v1' },
   { k2:'v2' },
   { k3:'v3' }
];
let newObj={};

array.forEach((obj) => { 
  let key = Object.keys(obj)[0];
  newObj[obj[key]]=key;
})  
console.log(newObj)

edited Feb 02 '19 at 16:31

answered Feb 02 '19 at 15:33

mplungjan

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score -2 · Answer 7 · edited Feb 02 '19 at 15:38

-2

your answer..

var array = [
  { k1: v1 },
  { k2: v2 },
  { k3: v3 }
];

function arrayToObject(array) {
  obj = {};
  for (i = 0; i < array.length; i++) {
    o = array[i];
    key = Object.keys(o)[0];
    obj.key = o.key;
  }
  return obj;
}


console.log(arrayToObject(array))

edited Feb 02 '19 at 15:38

mplungjan

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answered Feb 02 '19 at 15:35

Ande Caleb

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Your code does not run - and when the error is fixed it does not produce the correct result. – mplungjan Feb 02 '19 at 15:38

How can i get an object from an array of objects

7 Answers7