JavaScript

Variables

Understanding var, let, and const — scope, hoisting, temporal dead zone, and best practices.

Scope

Understanding global, function, and block scope — lexical scoping, scope chain, and closures.

Closures

Understanding closures — how functions retain access to their lexical scope, practical use cases, and common interview questions.

Debounce - Concepts & Polyfill

Implement a debounce function that delays invoking a function until after a specified wait period has elapsed since the last invocation.

Throttle

Implement a throttle function that ensures a function is called at most once every specified milliseconds.

Event Emitter

Implement an Event Emitter class with on, off, emit, and once methods — a fundamental publish-subscribe pattern.

Promise.all

Implement Promise.all — a function that resolves when all promises in an iterable have resolved, or rejects with the first rejection.

Deep Clone

Implement a deep clone function that creates a complete copy of a JavaScript value, handling objects, arrays, nested structures, and edge cases.