Arrays, Objects & Iteration

Most real data isn’t a single value, it’s a collection: a list of items, or a record with several named fields. This module covers arrays for ordered lists and objects for labeled data, plus the tools JavaScript gives you to pull them apart, reshape them, and loop over them.

Why This Matters

Arrays and objects are how JavaScript represents almost everything: a list of users, the response from a server, the settings for a form. The functions you just learned become far more useful once you have real data structures to apply them to.

What You’ll Learn

• Arrays, and the methods you’ll reach for constantly (.map(), .filter(), .reduce(), and more)
• Objects, object methods, and nested objects
• Destructuring, for pulling values out of arrays and objects by shape
• Spread and rest operators, for copying, merging, and collecting values
• Optional chaining and nullish coalescing, for safely reading deeply nested values
• Iterating over arrays and objects with the right loop for each

Outcome

By the end of this module, you’ll be able to build, reshape, and loop over the two data structures that show up in almost every JavaScript program you write.

Let’s get started.