• Components

• JSX

• Props

• State

• Events

• Conditional rendering

• Lists

• Forms

• Hooks

• useState

• useEffect

• useRef

• Context

• Custom hooks

• Component architecture

Then progress toward:

• Routing

• Data fetching

• State management

• Performance

• Server-side rendering concepts

For modern React applications, learn Next.js after React fundamentals.

🟣 PHASE 16 — TypeScript

In 2026, TypeScript is an important addition to a JavaScript developer's toolkit.

Learn:

• Type annotations

• Primitive types

• Arrays

• Objects

• Functions

• Interfaces

• Type aliases

• Union types

• Intersection types

• Generics

• Enums

• Type narrowing

• Utility types

• unknown

• never

• Type inference

• Modules

• Type-safe APIs

Don't use TypeScript as a substitute for learning JavaScript fundamentals.

🟣 PHASE 17 — Testing

Learn:

• Unit testing

• Test structure

• Assertions

• Mocking

• Test isolation

Tools:

• Vitest

• Jest

Browser testing

Learn tools such as:

• Playwright

• Cypress

Understand:

• Unit tests

• Integration tests

• End-to-end tests

🟣 PHASE 18 — Tooling

Become comfortable with the modern JavaScript ecosystem.

Package management

• npm

• package.json

• package-lock.json

• Semantic versioning

Also understand alternatives such as:

• pnpm

• Yarn

Build tooling

Understand the purpose of:

• Vite

• Bundlers

• Transpilation

• Minification

• Code splitting

• Tree shaking

You don't need to memorize every configuration option.

🟣 PHASE 19 — Code Quality

Learn professional development practices.

• ESLint

• Prettier

• Naming conventions

• Project structure

• Error handling

• Logging

• Environment configuration

• Git

• GitHub

• Code reviews

• Documentation

• Clean code

• Refactoring

🟣 PHASE 20 — Security

JavaScript developers should understand:

• XSS

• CSRF

• CORS

• SQL injection

• Authentication

• Authorization

• Password hashing

• JWT

• Sessions

• Secure cookies

• Input validation

• Dependency vulnerabilities

• Secrets management

🟣 PHASE 21 — Performance

Learn how to make JavaScript applications faster.

Browser performance

• Rendering

• Reflow

• Repaint

• DOM performance

• Lazy loading

• Code splitting

• Caching

• Debouncing

• Throttling

JavaScript performance

• Memory usage

• Garbage collection

• Memory leaks

• Profiling

• Expensive operations

• Big-O basics

🟣 PHASE 22 — Advanced Web APIs

Eventually explore:

• Web Workers

• Service Workers

• WebSockets

• Server-Sent Events

• IndexedDB

• Web Components

• Streams

• Notifications

• WebRTC basics

These are advanced/specialized topics, so don't let them distract you from core JavaScript.

🤖 PHASE 23 — JavaScript + AI in 2026

Modern JavaScript developers should also understand how applications integrate AI.

Learn:

• Calling AI APIs

• Streaming responses

• Structured outputs

• Tool/function calling concepts

• Embeddings basics

• Vector databases

• RAG fundamentals

• Authentication and API-key security

• Building AI-powered web applications

The goal isn't to become an AI researcher.

It's to know how to build useful AI features into JavaScript applications.

🧠 PHASE 24 — Problem Solving & DSA

Learn enough DSA to become a strong programmer and prepare for interviews.

Data structures