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CS Notes

Overview

What Is TypeScript?

Section titled “What Is TypeScript?”

TypeScript is JavaScript with an extra safety layer. You still write code that looks like JavaScript, but now you can describe what kind of data your code expects.

This helps catch mistakes early, before your app runs in the browser or on the server.

graph LR A[TypeScript Code] --> B[Type Checking] B --> C[tsc Compiler] C --> D[JavaScript Output] D --> E[Browser or Node.js]

Why Teams Use TypeScript

Section titled “Why Teams Use TypeScript”

Safer Refactoring

You can rename, move, and improve code with much more confidence.

Clear APIs

Function parameters and return values are explicit, so code explains itself.

Fewer Runtime Bugs

Many common mistakes are found at compile time.

Better Tooling

Editors provide stronger autocomplete, hints, and navigation.

What You Will Learn In This Track

Section titled “What You Will Learn In This Track”
  1. TypeScript basics, compiler, and setup.
  2. Built-in types, inference, annotation, and strict mode.
  3. Functions, optional/default/rest params, void, and never.
  4. Objects, interfaces, type aliases, intersections, and class basics.
  5. Unions, literals, narrowing, and exhaustive checks.
  6. Arrays, tuples, enums, and modern alternatives.
  7. Generics from beginner to advanced constraints.
  8. Utility, mapped, and conditional types with keyof, typeof, and infer.
  9. Type assertions, debugging common TS issues, and practical tsconfig setup.
  10. Real interview patterns used in production codebases.
  11. React with TypeScript: props, state, events, hooks, forms, context, and real app patterns.

Compile Time vs Runtime

Section titled “Compile Time vs Runtime”

TypeScript checks your code for type correctness.

let age: number = "25"; // Error here