Module 6 · 7 chapters

How JavaScript Works

JavaScript looks simple on the surface, but the engine does a lot of work behind the scenes. Variables are hoisted, functions create new execution contexts, the call stack tracks nested calls, and the prototype chain resolves property lookups.

This module is for developers who want to stop guessing and start understanding. Visual diagrams of the call stack, heap, and scope chain make abstract concepts concrete — and directly improve your debugging skills in real projects.

Chapters in this module

Execution ContextEvery time JavaScript runs code, it creates an execution context — a environment holding variables, this, and a link to outer scopes. See how global and function contexts are created, executed, and destroyed.
HoistingHoisting moves declarations to the top of their scope during compilation — which is why functions can run before their line and var reads as undefined instead of throwing.
Call StackThe call stack tracks which function is running now and which callers are waiting to resume. Push on every call, pop on every return — visualize recursion, nested calls, and stack overflow errors.
Memory ManagementJavaScript allocates memory automatically and reclaims unreachable objects via garbage collection — but lingering references can still leak memory in long-lived single-page apps.
Advanced ClosuresLearn Advanced Closures in JavaScript — covering Currying, Partial Application, Module Pattern, Memoization with interactive visual examples and step-by-step explanations.
PrototypesEvery JavaScript object inherits from another object through the prototype chain — the mechanism behind shared methods, Object.create, and how classes actually work under the hood.
Prototype ChainLearn Prototype Chain in JavaScript — covering Chain Visualization, Built-in Chains, instanceof, Property Shadowing with interactive visual examples and step-by-step explanations.

Start with Execution Context