TypeScript Essentials

Why it matters

TypeScript catches bugs before they ship and documents intent through types.

Core steps

• Enable strict mode for the best signals.
• Define interfaces for data models and prefer readonly where possible.
• Use discriminated unions to model state machines cleanly.
• Add generics to utilities to keep them flexible.

Pattern: Narrowing

type Result = { ok: true; data: string } | { ok: false; error: string };

function handle(result: Result) {
  if (result.ok) return result.data;
  throw new Error(result.error);
}