01 — Setup & Configuration

Core Concepts

• TypeScript compiles (transpiles) .ts files to plain JavaScript via tsc
• tsconfig.json is the project configuration file — controls compiler behavior
• Strict mode enables all strict type-checking flags at once
• target sets the JS version output (ES5, ES2015, ES2022, ESNext)
• module sets the module system (CommonJS, ESNext, NodeNext)
• outDir / rootDir control where compiled JS goes
• watch mode recompiles automatically on save
• strict: true enables: strictNullChecks, noImplicitAny, strictFunctionTypes, strictBindCallApply, etc.

Key tsconfig Options

When to Use

• Any project longer than a script — use TypeScript
• Always start with strict: true and only relax if needed
• Use noEmit: true when a bundler (Vite, webpack) handles compilation