Advanced

TypeScript · Proficient - advanced patterns and performance

• Narrowing: typeof, in, instanceof, and type guardsYou master type narrowing mechanisms and write your own predicates to make unions more reliable.
• Advanced generics: constraints and defaultsYou constrain your type parameters with extends and provide defaults to build ergonomic generic APIs.
• Utility types: Partial, Pick, Omit, Record, ReturnTypeYou derive types from a single source with the built-in utilities to eliminate duplication and the drift it causes.
• never, exhaustiveness, and advanced discriminated unionsYou model your states with discriminated unions and lock in their exhaustiveness with the never type.
• Strict tsconfig: key options and common errorsYou understand what strict mode actually enables and know how to handle the typical errors it reveals in an existing project.