Data Structures and Algorithms with JavaScript

Chapter 2. Arrays

The array is the most common data structure in computer programming. Every programming language includes some form of array. Because arrays are built-in, they are usually very efficient and are considered good choices for many data storage purposes. In this chapter we explore how arrays work in JavaScript and when to use them.

JavaScript Arrays Defined

The standard definition for an array is a linear collection of elements, where the elements can be accessed via indices, which are usually integers used to compute offsets. Most computer programming languages have these types of arrays. JavaScript, on the other hand, has a different type of array altogether.

A JavaScript array is actually a specialized type of JavaScript object, with the indices being property names that can be integers used to represent offsets. The specification states that array indices are converted to a string before storage, but most JavaScript engines perform optimizations under the hood to make the operation more efficient.

Note

One of the better descriptions of JavaScript Arrays and how they work is “Arrays in JavaScript” by Dr. Axel Rauschmayer.

While JavaScript arrays are, strictly speaking, JavaScript objects, they are specialized objects categorized internally as arrays. The Array is one of the recognized JavaScript object types, and as such, there is a set of properties and functions you can use with arrays.

Using Arrays

Arrays in JavaScript are very flexible. There are several ...