A deep dive into the parts of JavaScript functions that everyone has to learn the hard way — closures, the `this` binding, `call` / `apply` / `bind`, higher-order functions, and the patterns built on top of them.

Introduction to JavaScript functions — function declarations, function expressions, arrow functions, parameters, default values, rest/spread, return values, and the difference between calling and referencing.

A practical guide to branching in modern JavaScript — truthy and falsy rules, if / else if / else, switch, the ternary operator, short-circuit evaluation, optional chaining (?.), and nullish coalescing (??).

A modern, practical tour of JavaScript arrays — literal vs constructor creation, sparse-array gotchas, the full iteration toolkit (forEach, map, filter, reduce, flat, find, some, every), destructuring and spread, and when to reach for typed arrays.