Before you begin
Prerequisites
Hidden — select the eye to show
Block 03 · TYPED JAVASCRIPT PATH
TypeScript
Seventeen imported modules from first type annotations through advanced conditional and mapped types.
21 modules88 activitiesAbout 50 hoursBeginner to advancedLesson → Quiz → Exercise → Project
What you will master
Course outcomes
Hidden — select the eye to show
Final proof of skill
Mastery capstone
Hidden — select the eye to show
Completion standard
Earn the Mastery title
Hidden — select the eye to show
Progress one module at a time
Course map
- Module 014 activities
What is TypeScript?
TypeScript is a language developed by Microsoft in 2012 — it is JavaScript with a type system. You specify what types your variables, functions, and objects should hold, and TypeScript compiles ("transpiles") that down to plain JavaScript that runs anywhere JS runs.
LessonQuizExerciseProjectStart module - Module 024 activities
Primitive Types
TypeScript's core primitives are string (text), number (any numeric value — int, float, hex), and boolean (true/false).
LessonQuizExerciseProjectStart module - Module 034 activities
Arrays & Tuples
Arrays hold multiple values of the same type — TypeScript enforces this at compile time.
LessonQuizExerciseProjectStart module - Module 044 activities
Objects & Interfaces
An interface defines the shape of an object — which properties it has, their types, and whether they are optional or readonly. Interfaces are reusable and can be extended.
LessonQuizExerciseProjectStart module - Module 054 activities
Functions
Functions are reusable blocks of code. In TypeScript you can explicitly type parameters and return types, preventing errors like passing the wrong argument type or misusing a return value.
LessonQuizExerciseProjectStart module - Module 064 activities
Union Types
Union types let a variable hold values of more than one type using the | (pipe) operator.
LessonQuizExerciseProjectStart module - Module 074 activities
Classes
Classes are blueprints for creating objects. TypeScript adds access modifiers and strict typing on top of JavaScript classes.
LessonQuizExerciseProjectStart module - Module 084 activities
Generics
Generics let you write reusable code that works with different types while staying type-safe. They use the <T> syntax.
LessonQuizExerciseProjectStart module - Module 094 activities
Enums
Enums let you define a set of named constants, making code more readable and self-documenting.
LessonQuizExerciseProjectStart module - Module 104 activities
Type Narrowing
Type narrowing is how TypeScript figures out a more specific type from a broad one using guards or assertions.
LessonQuizExerciseProjectStart module - Module 114 activities
Modules
Modules split code into separate files using export and import.
LessonQuizExerciseProjectStart module - Module 124 activities
Utility Types
TypeScript ships with built-in generic helper types: Partial, Required, Pick, Omit, Record, ReturnType, NonNullable.
LessonQuizExerciseProjectStart module - Module 134 activities
Decorators
Decorators are functions that wrap other code. They start with @ and sit above a class, method, property, or parameter.
LessonQuizExerciseProjectStart module - Module 144 activities
tsconfig.json
TypeScript uses tsconfig.json to understand how to compile your project. Generate it with `tsc --init`.
LessonQuizExerciseProjectStart module - Module 154 activities
TypeScript + React
TypeScript enhances React with typed props, typed state, typed refs, and typed events.
LessonQuizExerciseProjectStart module - Module 164 activities
TypeScript + Node.js
TypeScript works seamlessly with Node.js and Express for type-safe server code.
LessonQuizExerciseProjectStart module - Module 174 activities
Advanced Types
The deep end of TypeScript: conditional types, mapped types, template literal types, and infer.
LessonQuizExerciseProjectStart module - Module 185 activities
Strict Type Safety & Error Modeling
Use strict mode, unknown, never, discriminated results, exhaustive checks, and safe error boundaries.
LessonQuizExerciseReviewProjectStart module - Module 195 activities
Typed APIs & Runtime Validation
Separate compile-time types from untrusted runtime data and validate API boundaries before values enter the application.
LessonQuizExerciseReviewProjectStart module - Module 205 activities
TypeScript Testing & Architecture
Test typed functions, design dependency boundaries, use fakes, and keep domain logic independent from frameworks.
LessonQuizExerciseReviewProjectStart module - Module 215 activities
TypeScript Mastery Capstone
Combine strict types, generics, validation, modules, tests, and framework integration in one production-style application.
LessonQuizExerciseReviewProjectStart module