Arrays

Objects allow you to store keyed collections of values. That’s fine.

But quite often we find that we need an ordered collection, where we have a 1st, a 2nd, a 3rd element and so on. For example, we need that to store a list of something: users, goods, HTML elements etc.

It is not convenient to use an object here, because it provides no methods to manage the order of elements. We can’t insert a new property “between” the existing ones. Objects are just not meant for such use.

There exists a special data structure named Array, to store ordered collections.

Declarations

There are two syntaxes for creating an empty array:

let arr = new Array();
let arr = [];

Almost all the time, the second syntax is used. We can supply initial elements in the brackets:

let fruits = ["Apple", "Orange", "Plum"];

Array elements are numbered, starting with zero.