TypeScript 5.x Features Every Professional Developer Should Know
TypeScript 5.x introduced decorators, const type parameters, and variadic tuple improvements that change how we write application code. This practical guide covers what matters most.
Decorators Are Finally Stable
After years of experimental status, TypeScript 5.0 shipped stable decorators aligned with the TC39 stage 3 proposal. This means you can finally use them in production code without worrying about breaking changes. Class decorators, method decorators, and property decorators are all supported.
Const Type Parameters
TypeScript 5.0 added the `const` modifier for type parameters, allowing you to infer the most precise type from a literal argument. This is particularly useful for building type-safe configuration objects and builder patterns.
Variadic Tuple Improvements
Better inference for variadic tuples means more ergonomic generic function signatures. Libraries like tRPC and Zod have already updated to leverage these improvements, resulting in significantly better IDE autocomplete.
Resolution Customization
The new `customConditions` and `resolution-mode` options give you fine-grained control over how modules resolve. This is critical for monorepo setups with dual CJS/ESM packages.
Practical Adoption Tips
Enable `"strict": true` if you haven't already — it catches entire classes of bugs at compile time. Add `"exactOptionalPropertyTypes": true` next for even stricter object property checking. These two settings together eliminate most runtime type errors we see in production codebases.
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