Learn JavaScript Arrays in 30 Minutes

Discover what JavaScript arrays are, a list of items, and learn how to set up the environment with HTML files, VS Code, the Live Server extension, and browser tools.

Learn how to create arrays in JavaScript using const numbers and square brackets, log them with console.log, and read their zero-based indices and length.

Learn how to retrieve items from a JavaScript array by index (e.g., index two for the third item), and understand that out-of-range indices yield undefined, unlike Python's negative indexing.

Master looping over arrays in JavaScript using for of, index-based, and for each method to output every item with console.log.

Learn how to append items to an array using push and unshift, add to end or beginning, check length and index positions, and update a value at a given index.

Learn three common ways to delete items from a JavaScript array: splice by index, and pop or shift to remove the last or first item and return the removed value.

Learn how to create and iterate an array of objects in JavaScript using a for-of loop, with a leaderboard example that stores name and score and renders rows in html.

Explore multidimensional arrays as arrays of arrays, using a grid example to access elements by index pairs, visualize with console.table, and traverse with nested for of loops.

Transform items inside an array using the map method with a callback arrow function to update every element, illustrated by doubling numbers 1–5 and transforming lists into objects.

Filter arrays to create an array of items that meet a condition, without mutating the original. Use a predicate, such as excluding names containing a, with leaderboard and Vue.js examples.