Adding an item at an arbitrary location in javascript array

Question

Say I have the following array:

const months = ['January', 'February', 'March', 'April', 'June'];

And I want to add the item December at position 11. From what I know I would do:

months.splice(11, 0, "December");

I would like it to be added in position 11 and positions 5 to 10 to be "null" or "undefined". However when I do:

months.indexOf("December")

I get a result of 5 and printing the array returns December as the last position right after June.

Is there a way to add this item at the specified position?

Thanks

Nina Scholz · Accepted Answer · 2020-06-18 05:40:33Z

1

Just take the index and assign the value. Unset items are undefined, because you got a sparse array.

const months = ['January', 'February', 'March', 'April', 'June'];

months[11] = "December";

console.log(months.indexOf("December"));
console.log(months);

answered Jun 18, 2020 at 5:40

Nina Scholz

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Siva Kondapi Venkata · Accepted Answer · 2020-06-18 09:14:49Z

0

One more way to do is increase the array length and push the element.

const months = ['January', 'February', 'March', 'April', 'June'];

months.length = 11;
months.push("December");

console.log(months.indexOf("December"));
console.log(months.findIndex(x => x === "December"));
console.log(months);

answered Jun 18, 2020 at 9:14

Siva Kondapi Venkata

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