Lesson 8 • Advanced
TypeScript Best Practices 🏆
Real-world patterns, strictness settings, code organization, and anti-patterns to avoid — everything you need for production TypeScript codebases.
What You'll Learn in This Lesson
- • Recommended
tsconfig.jsonstrictness settings - • Clean patterns: type inference, discriminated unions, branded types
- • Project structure and file organization
- • Type export patterns and barrel exports
- • Anti-patterns to avoid in production code
1️⃣ Strictness Settings
Always enable strict: true in your tsconfig.json. This single flag enables all strict checks. Add noUncheckedIndexedAccess for even stricter array/object access safety.
Try It: Strictness
Essential tsconfig.json settings for production
// TypeScript Strictness Settings
console.log("=== tsconfig.json Strict Settings ===");
console.log();
let settings = [
{ flag: "strict", desc: "Enables ALL strict checks below (always use this!)" },
{ flag: "strictNullChecks", desc: "null/undefined not assignable to other types" },
{ flag: "strictFunctionTypes", desc: "Strict function parameter type checking" },
{ flag: "strictPropertyInitialization", desc: "Class properties must be initialized" },
{ flag: "noImplicitAny", desc: "Err
...2️⃣ Clean Patterns
These four patterns will elevate your TypeScript code: prefer inference, use discriminated unions for state, exhaustive checking for safety, and branded types to prevent ID mix-ups.
Try It: Clean Patterns
Inference, discriminated unions, exhaustive checks, branded types
// Clean TypeScript Patterns
console.log("=== Pattern 1: Prefer Type Inference ===");
console.log();
console.log("// ❌ Over-annotated:");
console.log("const name: string = 'Alice';");
console.log("const nums: number[] = [1, 2, 3];");
console.log();
console.log("// ✅ Let TS infer:");
console.log("const name = 'Alice'; // inferred string");
console.log("const nums = [1, 2, 3]; // inferred number[]");
console.log("// Only annotate when inference isn't enough.");
console.log();
console.lo
...3️⃣ Code Organization
Good project structure keeps types discoverable and maintainable. Split types by domain, use barrel exports for clean imports, and derive types instead of duplicating them.
Try It: Organization
File structure, type exports, barrel exports, and anti-patterns
// Code Organization & Project Structure
console.log("=== File Organization ===");
console.log();
console.log("src/");
console.log("├── types/");
console.log("│ ├── index.ts // Re-export all types");
console.log("│ ├── user.ts // User-related types");
console.log("│ ├── api.ts // API response types");
console.log("│ └── common.ts // Shared utility types");
console.log("├── components/");
console.log("│ ├── Button.tsx // Component + its Props in same
...⚠️ Common Mistakes
@ts-ignore — Use @ts-expect-error instead. It errors when the suppressed issue is fixed, preventing stale suppressions.strict: true — Without it, TypeScript misses null checks, implicit any, and other critical bugs.tsc --noEmit in CI to catch type errors before deployment. Zero runtime cost, maximum safety.📋 Quick Reference — Best Practices
| Practice | Rule |
|---|---|
| Strict mode | Always enable strict: true |
| Avoid any | Use unknown + narrow |
| State modeling | Discriminated unions |
| Type inference | Don't over-annotate |
| Derive types | Use Partial/Pick/Omit |
| CI check | tsc --noEmit in pipeline |
🎉 Course Complete!
Congratulations! You've completed the TypeScript course! You now have the skills to write type-safe, production-ready TypeScript code. Build amazing things! 🚀
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