Learn JavaScript - JS Course

Learn Simpli

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About this app

Learn JavaScript the smart way — from your very first line of code to advanced interview-level concepts. Whether you're a complete beginner or brushing up for your next job interview, Learn JavaScript gives you a structured, hands-on path with clear explanations, real code examples, visual diagrams, quizzes, and 190+ coding problems solved in JavaScript.

Everything works offline. No sign-up required to start learning.

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WHAT YOU'LL LEARN
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• 435 lessons across 39 chapters — basics to advanced
• Modern JavaScript (ES6+): let/const, arrow functions, destructuring, spread/rest, modules
• Asynchronous JS: callbacks, promises, async/await, the event loop
• The DOM: selecting, manipulating and handling events
• Closures, scope, hoisting and the "this" keyword
• Arrays, objects, strings, maps, sets and typed arrays
• Prototypes, classes and object-oriented JavaScript
• Error handling, custom errors and debugging
• Design patterns in JavaScript
• Under the hood: how the V8 engine and JS runtime work

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FEATURES
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📘 Structured lessons — every topic broken into Theory & Fundamentals, Core Mechanics, Best Practices & Pitfalls, and a Quick Summary
🖼️ Visual diagrams — clear SVG illustrations that make tricky concepts click
💻 Real code examples — syntax-highlighted snippets you can read and copy
🧠 840+ quiz questions across 28 topics with answer explanations
🎯 190+ interview coding problems — Numbers, Strings, Arrays, Stacks, Trees, Linked Lists, Queues, Matrices, Patterns — each with a JavaScript solution
🏢 Company-style questions (Google, Amazon, Microsoft, Oracle patterns)
📶 Fully offline — learn anywhere, no internet needed after install
🌙 Clean, distraction-free reading with light and dark themes
🔖 Bookmarks and reading progress tracking

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PERFECT FOR
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• Beginners learning to code for the first time
• Students preparing for exams and assignments
• Developers preparing for technical interviews
• Anyone who wants a solid, practical JavaScript foundation

Learn JavaScript at your own pace and build a strong, practical foundation — one chapter at a time.

What’s new

🎯 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