Methods

Summary

Functions attached to objects/arrays (`.push`, `.map`, `.toUpperCase`) that operate on the data they belong to — knowing the built-in method library well speeds up everyday coding a lot. Knowing method behavior includes understanding return values, mutation, callback arguments, chaining, and whether an operation creates a new value or changes the original.

• 1Skim MDN's Array and String method reference pages once, fully. Validate your understanding by applying it in a small practical example.
• 2Practice chaining methods together (`.filter().map().reduce()`). Test it with at least one normal case and one edge case so you can explain the behavior confidently.
• 3Learn which array methods mutate the original array and which return a new one.