Master JavaScript from basics to advanced
A callback is a function passed into another function to be called later. Learn synchronous and asynchronous callbacks, error-first patterns, and how callbacks power event handlers and async code.
A closure is a function that remembers the variables from the scope where it was created, even after that scope is gone. Learn how closures work, why they matter, and what you can build with them.
Closures are not just an interview question. Learn real-world closure patterns: event handlers, debouncing, memoization, module patterns, and stateful callbacks.
Closures keep outer variables alive. When you do not clean them up, they become memory leaks. Learn the common leak patterns and how to fix each one.
An IIFE is a function that runs the moment it is defined. Learn the syntax, why it was essential before ES6 modules, and where IIFEs still make sense today.
Recursion is a function that calls itself. Learn base cases, the call stack, practical examples like factorial and tree traversal, and when recursion beats iteration.
Deep recursion crashes the call stack. Learn how to avoid stack overflow with tail recursion, trampolines, iteration conversion, and practical depth limits.
Learn four ways to create arrays in JavaScript: literal notation, the Array constructor, Array.of, and Array.from. Each method has different strengths.
Learn how to read, update, and manage array elements using bracket notation, the length property, and index-based access in JavaScript.
Learn how push() and pop() add and remove elements from the end of a JavaScript array, what they return, and when to use each one.
Learn how shift() and unshift() add and remove elements from the beginning of a JavaScript array. Understand the performance cost and when to reach for these methods.
Build a full state management system in vanilla JavaScript. Learn how to centralize state, derive computed values, handle async actions, and connect to the DOM without a framework.
