COURSE · 2 OF 6
JavaScript the language underneath
The language that runs the web — deep notes on how JavaScript actually executes, from the Execution Context through closures, promises, and the event loop.
- CHAPTERS
- 16
- FULL NOTES
- 4 h
- DIFFICULTY
- BEGINNER
WHAT YOU’LL LEARN
What you’ll learn
- The two-phase execution model — Memory Creation and Code Execution, end to end.
- The Call Stack — how LIFO drives every synchronous function call, return, and stack overflow.
- Hoisting and the Temporal Dead Zone — var vs function vs let/const/class, and the three different errors they produce.
- Variable Environments and lexical scoping — why same-named variables in different functions never collide.
- Pass by value vs pass by reference — primitives, objects, and the traps around reassignment.
- Common interview questions with the right mental models ready to deploy.
CHAPTERS
Chapters
- ○Execution Context
Memory + Code — the sealed container every JS program runs inside.
- ○How JS is Executed & Call Stack
The two phases of execution, and the LIFO stack that keeps track of where JS is.
- ○Hoisting in JavaScript
Why you can use variables and functions before declaring them — and why it sometimes breaks.
- ○Functions & Variable Environments
How each function creates its own isolated world of variables — and why same-named names never collide.
- ○window, this, undefined vs not defined
The global object, the this keyword, and two commonly confused concepts.
- ○Scope Chain, Scope & Lexical Environment
How JS finds variables — the lookup mechanism that powers closures and modules.
- ○let, const, Temporal Dead Zone, Block Scope & Shadowing
The modern declarations, their scoping rules, and the three errors they produce.
- ○Closures — The Complete Guide
Function + lexical environment — closures, setTimeout patterns, and data hiding.
- ○Functions, Callbacks, Event Loop, JS Engine & setTimeout
First class functions, callbacks, the event loop, V8, and why setTimeout lies.
- ○Higher-Order Functions, map, filter & reduce
Higher-order functions + map, filter, reduce — functional JS patterns and polyfills.
- ○Tricky JS Interview Questions: Data Types, Type Coercion, Equality & Gotchas
Data types, type coercion, == vs ===, NaN, truthy/falsy — the JS gotchas.
- ○Polyfills, this/call/apply/bind, Currying, Debounce, Promises & Coding Challenges
Polyfills, this/call/apply/bind, currying, debounce, deep clone — code these live.
- ○call/apply/bind, Currying & Promises — The Complete Guide
call/apply/bind with intent, currying as partial application, and the complete Promise surface.
- ○Callbacks & Promises — From Problem to Solution
Why callbacks break and how promises fix both Callback Hell and Inversion of Control.
- ○Creating Promises, Chaining, Error Handling & async/await
The producer side of promises and the modern way to write async code with async/await.
- ○JavaScript Complete Revision Guide
All 25 episodes plus bonus — one-look pre-interview revision with 50 rapid-fire output questions.