Why does adding values in JavaScript extends array length?

Question

What happens in the following code for me to get 101?

let myArray = [1, 2, 3];

myArray[100] = "beauty"

console.log(myArray.length);

Does this answer your question? Change array size by just adding element and no push javascript — fdermishin
– fdermishin, Commented Dec 17, 2020 at 20:27

j08691 · Accepted Answer · 2020-12-17 19:00:49Z

3

In JavaScript arrays are zero-based, so

let myArray = [1, 2, 3];

Has a length of three but the array element indices are 0, 1, and 2.

When you manually insert

myArray[100] = "beauty"

You put an element in the array with index 100 and then have elements 0-100 inclusive, so 101 array elements.

answered Dec 17, 2020 at 19:00

j08691

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2 Comments

Thanks I think i get it. 99 + 0+ 1+1

@jessi. Correct. 0-100 is 101 items. Like 0-10 is 11 items