Weird data lose in javascript while converting Array into Object

Question

I was just working with JavaScript objects and found this which i cant figure out . I created an array with few values and trying to convert that array into object using spread and new in JavaScript but for my surprise only the first value in the array is been put into the object with its type .

I have no need what exactly is happening in background

let array = [1970,1,1]
let object = new Object(array)

console.log(object)

Output :

Number {1970}

I was expecting {1970 , 1 , 1} object but actual output is Number {1970}

"trying to convert that array into object" - what? An array object already is an object. So what do you actually want to achieve? — Bergi
– Bergi, Commented Jul 16, 2019 at 14:11

Ghoul Ahmed · Accepted Answer · 2019-07-16 14:06:56Z

2

to convert array to object use Object.assign

Object.assign({},[1970,1,1])

or you can populate the object with the array elements

let array = [1970,1,1];
var obj = new Object();
Array.prototype.push.apply(obj, array);
console.log(obj);

edited Jul 16, 2019 at 14:06

answered Jul 16, 2019 at 13:46

Ghoul Ahmed

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2 Comments

Jakka rohith Over a year ago

Can you tell me whats up with my approach why all other values expect the first is discarded

Ghoul Ahmed Over a year ago

you cannot use array as constructor for Object , to fix your approach, you should use let obj = new Object(); Array.prototype.push.apply(obj, array);

Dupocas · Accepted Answer · 2019-07-16 13:46:01Z

2

The closest thing you could do is:

const object = {...array}

Which will give you the output:

{0: 1970, 1:1, 2:1}

answered Jul 16, 2019 at 13:46

Dupocas

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3 Comments

Jakka rohith Over a year ago

Yes. Can you tell me what is wrong with my approach

Dupocas Over a year ago

In general you should avoid using the literal constructor new Object. If you pass an array to it will just return the array back.

Dupocas Over a year ago

when using the spread operator const obj = {...array} you are telling: Hey make me an object with a property for each item of this array, and this property name will be the element's index

Mamun · Accepted Answer · 2019-07-16 13:46:19Z

1

You can try with Object.assign()

let array = [1970,1,1];
let object = Object.assign({}, array);
console.log(object);

answered Jul 16, 2019 at 13:46

Mamun

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Comments

Naveen Kumar V · Accepted Answer · 2019-07-16 15:18:12Z

0

It works in the Chrome (Version 75).

Check the following code, if in case you are expecting the following behavior.

CODE:

let array = [1970,1,1];
let obj = {}, i = 0;
for(var element in array) obj[i++] = array[element];
console.log(obj);

answered Jul 16, 2019 at 15:18

Naveen Kumar V

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