Annotations Design Patterns

Design patterns, resilience and caching for TypeScript, with standard TC39 decorators or composable functions. Zero runtime dependencies, strict types and granular imports.

npm install annotations-design-patterns

These docs cover 2.3.0. The migration guide identifies new features and the APIs that retain experimental status.

Getting started

API reference

With decorators

import { Singleton, Retry, Timeout, Fallback } from 'annotations-design-patterns';

@Singleton
class ApiClient {
  @Fallback<User[]>([])
  @Retry({ attempts: 3, delayMs: 200, backoffFactor: 2 })
  @Timeout(5000)
  async fetchUsers(): Promise<User[]> {
    /* ... */
  }
}

With functions

import { fallback, retry, timeout } from 'annotations-design-patterns/operators';
import { pipe } from 'annotations-design-patterns/pipe';

const fetchUsers = pipe(
  loadUsers,
  fallback<object, readonly [], User[]>([]),
  retry({ attempts: 3, delayMs: 200, backoffFactor: 2 }),
  timeout(5000),
);

See the decorator, operator and 2.3 migration guides. The shared API reference has its own symbol search in English; guide search uses the selected language.