How do array sizes work in Javascript

Question

In JavaScript, if you set an array to be of size 5 ( var foo = new Array(5); ), is this just an initial size? Can you expand the number of elements after it is created. Is it possible to do something like this as well - arr = new Array() and then just assign elements one by one? Thanks in advance :-)

Answer 1

Yes it is just an initial size, and it is not required. If you don't use a single number, you can immediately populate.

It is also more common to use the simpler [] syntax.

var arr = ['something', 34, 'hello'];

You can set (or replace) a specific index by using brackets:

arr[0] = "I'm here replacing whatever your first item was";

You can add to the end by using push:

arr.push('add me');

There may be faster performance in some browsers if you do it like this instead:

arr[arr.length] = 'add me';

You can add something at any index.

You can remove an item completely using splice:

arr.splice(0, 1); // remove first item in the array (start at index 0, with 1 being removed)