Frontend Engineer
Master the web: JavaScript and TypeScript end-to-end, then build the tools you depend on every day — a virtual-DOM framework, JSON parser, markdown renderer.
Course sequence
- 01
JavaScript Fundamentals
Not startedLearn the language that runs every browser and most of the backend internet. Variables, functions, arrays, objects, async — every lesson is hands-on with real Node.js execution.
beginnerjavascript15 lessons~4h - 02
JavaScript Intermediate
Not startedLevel up from JavaScript Fundamentals. Async/await, Promises, closures, the prototype chain, error handling, generators, regex. The features you reach for once you've outgrown the basics.
intermediatejavascript15 lessons~4h - 03
JavaScript Advanced
Not startedBeyond JavaScript Intermediate. Generators + async iteration, Proxy/Reflect, prototype chain in depth, weak references, V8 perf basics. The features behind serious JS frameworks and tooling.
advancedjavascript8 lessons~2h - 04
TypeScript Fundamentals
Not startedTypeScript is JavaScript with a type system. The same code that runs in browsers, but the compiler catches errors before you ship. Static types, interfaces, generics — every lesson is hands-on with real ts-node execution.
intermediatetypescript15 lessons~4h - 05
TypeScript Intermediate
Not startedLevel up from TypeScript Fundamentals. Generics, union and intersection types, narrowing, mapped types, utility types. The features that make TypeScript's type system genuinely useful, not just JavaScript with annotations.
intermediatetypescript8 lessons~2h - 06
TypeScript Advanced
Not startedBeyond TypeScript Intermediate. Conditional types in depth, template literal types, recursive types, declaration files, branded types, type guards. The features that make TypeScript's type system genuinely magical.
advancedtypescript7 lessons~2h - 07
Build a Frontend Framework (Virtual DOM)
Not startedBuild a tiny React: virtual DOM tree, components as functions, props + children, the diffing reconciliation algorithm with keys, useState and useEffect hooks, event delegation, and the architecture behind React, Vue, Preact.
advanced14 lessons~4h - 08
Build Your Own JSON Parser
Not startedBuild a fully RFC 8259-compliant JSON parser from scratch. You'll tokenize structural characters, decode escape sequences and Unicode, parse numbers with strict grammar, and recursively assemble objects and arrays. By the end you'll deeply understand how json.loads, JSON.parse, and every other parser actually works.
beginner12 lessons~3h - 09
Build a Markdown to HTML Converter
Not startedBuild a Markdown parser following CommonMark: headings, paragraphs, emphasis, links, images, lists, code blocks, blockquotes, horizontal rules. Then add GFM extensions (tables, strikethrough). The foundation of every README, blog post, and static site generator.
beginner20 lessons~5h - 10
Build a Template Engine
Not startedBuild a Jinja2-style template engine: tokenize {{ var }} and {% tag %}, parse to AST, resolve variables, apply filters with auto-escaping, evaluate if/for control flow, and implement template inheritance with extends/block. Powers Flask, Ansible, Salt, Helm.
intermediate10 lessons~3h
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