Generics enable writing code that works with multiple types while maintaining type safety. Beyond basic generic functions, TypeScript supports sophisticated patterns including conditional types, mapped types, and template literal types. Mastering these patterns enables building robust, reusable abstractions.
Constraint Patterns
Generic constraints limit acceptable type parameters using extends clauses. Constraining to object types enables property access. Constraining to specific interfaces ensures required methods exist. Multiple constraints combine requirements for complex type bounds.
- Use extends to constrain generic parameters to specific shapes
- Apply keyof for type-safe property access on generic objects
- Leverage infer in conditional types to extract type information
- Create mapped types transforming object types systematically
- Combine utility types like Partial, Required, and Pick for common transformations
Type Inference Optimization
TypeScript infers generic parameters from usage when possible. Explicit type parameters become necessary when inference fails or produces unexpected results. Understanding inference rules helps write generics that feel natural to use while maintaining precise types.