TypeScript Best Practices for Production Code in 2026

TypeScript has become the default for serious JavaScript projects. But using TypeScript doesn't automatically mean your code is safe — you need to use it correctly. This guide covers 15 best practices that separate production-quality TypeScript from TypeScript that's just JavaScript with extra steps. 1. Enable Strict Mode — Always The single highest-leverage change you can make to a TypeScript project: // tsconfig.json { "compilerOptions": { "strict": true, "noUncheckedIndexedAccess": true, "noImplicitReturns": true, "exactOptionalPropertyTypes": true } } strict: true enables a bundle of safety flags: strictNullChecks — null and undefined are not assignable to other types strictFunctionTypes — function parameter types are checked contravariantly noImplicitAny — error when TypeScript infers any strictBindCallApply — bind, call, apply are type-checked noUncheckedIndexedAccess is not included in strict but is worth enabling: it makes array[0] return T | undefined instead of T, which preve