Push to undefined index in array

Question

Is there any better way to push something to undefined index in array instead of this:

// Just an example

let array = [];
let indexInArray = 0;
let data = "data";

// This throws error
// array[indexInArray].push(data);

for(let i = 0; i <= 1; i++) {
    if(array[indexInArray] == undefined) {
        array[indexInArray] = [data];
    } else {
       // This throws error if i = 0
       array[indexInArray].push(data);
    }
}

// array = [["data", "data"]];

I am looking for pushing to undefined index in array.

So I need to create array in index and then do push().

What do you want to achieve with that?

Neel Rathod
– Neel Rathod

2019-08-30 20:05:55 +00:00
Commented Aug 30, 2019 at 20:05 — Neel Rathod
– Neel Rathod, Commented Aug 30, 2019 at 20:05

Kryten · Accepted Answer · 2019-08-30 20:06:05Z

2

I think what you're looking for is this:

const array = [];

array[42] ='hello';

You can set a value at a specific index in an array simply by assigning to that value.

answered Aug 30, 2019 at 20:06

Kryten

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6 Comments

John Doe Over a year ago

I am sorry. I edited my post. I need to push to array in index. I want to do this before always checking if array in index is undefined or not.

Neel Rathod Over a year ago

It's can't push anything in that array, In Javascript array [] and objects {} both typeof is objects, So here you assign a key value pair array[42] ='hello' into an array.

Neel Rathod Over a year ago

Even you can do this array[-1] = '-1'

John Doe Over a year ago

@NeelRathod I am looking for something like this. But I need to do this on index in array not in array.

Neel Rathod Over a year ago

@JohnDoe It seems like you want to convert array elements of undefined to it's index. Ex. [1,2, undefined] => [1,2,2]

|

Neel Rathod · Accepted Answer · 2019-08-30 20:48:58Z

0

You don't need to use push for that, you just need to do this arr[index] = data

const array = [1, 2, undefined];
const data = 'Neel';
array[3] = data;
array[10] = data;
console.log(array);

Note: If you assign a value on above max index then a value of between index will be undefined, Check above snippet for index 10

edited Aug 30, 2019 at 20:48

answered Aug 30, 2019 at 20:32

Neel Rathod

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6 Comments

John Doe Over a year ago

Sorry for misunderstanding. Look at my post. This is not my problem.

John Doe Over a year ago

I know that. But I want to push a few data to array[index]. I need array in array[index] and push into it.

Neel Rathod Over a year ago

Please put your expect output

John Doe Over a year ago

Done. I've already have not idea how to explain it better. Thanks for your time!

Neel Rathod Over a year ago

@JohnDoe Happy to help..Anything wrong with this answer? Please comment on, upvote or indeed accept answers. –

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