Introduction to JavaScript Arrays

In JavaScript, an array is a dynamic structure that contains a collection of data organized into an ordered list or sequence.

Arrays are often used to store related elements of the same type — but not necessarily — like strings, numbers, booleans, arrays, objects, and so on.

They allow developers to create complex structures such as stacks, queues, and matrices, that can then be used in sorting, searching, and filtering algorithms.

Learning objectives

In this module, you'll learn how to work with arrays: how to create them, access elements by index, modify their contents, and process collections of values using built-in methods.

Arrays are everywhere in Node.js applications: command-line arguments, file lines, CSV rows, database query results, API payloads, and lists of resources all end up being represented and manipulated as arrays.

After completing this module, you will be able to:

• Create arrays using the square brackets syntax and the Array.from() method.
• Access and modify array elements using user-defined and computed indexes.
• Add and remove elements using indexes and built-in array methods.
• Destructure arrays to extract specific elements into variables.
• Sort, find, and filter array elements using built-in methods.
• Process and transform string data by searching, replacing, extracting, and splitting substrings.
• Build scripts that process lists of values and produce deterministic, formatted outputs.