Learn JavaScript - JS Course

JavaScript makes sense once you understand three ideas: scope, the event loop and how objects share behaviour through prototypes. Most bugs and most interview questions come back to one of them. This app helps you learn JavaScript around those ideas, from your first variable to advanced patterns, fully offline.

435 Lessons from Basics to Advanced
Chapters cover variables, functions, arrays and objects, then ES6+, closures, prototypes, classes, modules and asynchronous code with promises and async/await. Each lesson has key points and highlighted code.

Visual Diagrams for Tricky Concepts
Diagrams show how the event loop, the call stack and the DOM actually work, so asynchronous code stops feeling like magic.

840 Quiz Questions
Quizzes across 28 topics explain every answer, from hoisting and closures to web workers and V8 internals.

190+ Interview Coding Problems
Practise problems on numbers, strings, arrays, stacks, trees and patterns, each with a JavaScript solution.

Learn Anywhere, No Login
Everything is stored in the app, so it works offline with no account, on a train, in class or anywhere without data.

Learn JavaScript one chapter at a time and the language will start to feel predictable.

For any questions or feedback, write to us at learnsimpli19@gmail.com.

Recent changes:
🎯 190+ interview coding problems, each with a JavaScript solution
🖼️ New visual diagrams across lessons to explain concepts faster
📘 Redesigned lessons — Theory, Core Mechanics, Pitfalls & Quick Summary
🧠 840+ quiz questions with answer explanations
🔓 First few problems now free to try
✨ Cleaner reading experience and tighter layouts