Master JavaScript from basics to advanced
Learn what unit testing is, why it matters, and how to write your first tests. Covers the arrange-act-assert pattern, what makes a good test, and what to test versus what to skip.
Set up Vitest, write fast unit tests with it, and run them with zero config. Covers test blocks, matchers, async testing, mock functions, and coverage reporting.
A JavaScript engine turns your code into machine instructions. Learn how V8, SpiderMonkey, and JavaScriptCore parse, compile, and run JavaScript.
An execution context is the environment JavaScript creates every time it runs code. Learn how global and function contexts, scope chains, and the creation phase work.
The call stack tracks which function is currently running using LIFO order. Learn how frames are pushed, popped, and how stack traces help debugging.
The call stack is the backbone of JavaScript's single-threaded execution. Learn how it connects to the heap, event loop, and memory management.
The call stack, task queue, and microtask queue decide what runs and when. Learn their differences and why Promise callbacks always beat setTimeout.
The event loop is the mechanism that lets JavaScript handle async operations while staying single-threaded. Learn its architecture and how it coordinates the call stack with task queues.
Microtasks and macrotasks are the two queue types that determine async callback order in JavaScript. Learn their differences and why Promise callbacks run before setTimeout.
V8 compiles JavaScript through a multi-tier pipeline: Ignition for fast startup and TurboFan for peak performance. Learn how parsing, bytecode, and JIT work together.
V8's internals include hidden classes, inline caching, and a generational garbage collector. Learn how these mechanisms make JavaScript execution fast.
Bytecode is the intermediate language between your JavaScript source and machine code. Learn how engines use bytecode for fast startup and how it feeds into JIT compilation.
