Generics
Generic Interfaces & Types
Master Generic Interfaces and Generic Type Aliases in TypeScript, API response wrappers, state management wrappers, and reusable data container contracts.
Last Updated: July 29, 2026
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10 min read
Like functions, Interfaces and Type Aliases can accept generic type parameters to model reusable data containers, API payload responses, and state wrappers.
1. Generic Interfaces
Add type parameters after the interface name:
2. Generic Type Aliases
Generic type aliases follow the exact same syntax:
3. Generic Callback Signatures
Generic type parameters can be attached to callback function definitions inside interfaces:
4. Interactive Code Playground
Test generic interfaces below:
5. Summary Table
| Pattern | Generic Syntax Example | Common Use Case | |
|---|---|---|---|
| Generic Interface | interface Box { value: T; } | API responses, repository pattern | |
| Generic Type Alias | type Result = T \ | Error | State wrappers, union containers |
type Nullable = T \| null | Codebase-wide type modifiers |