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Install the package

Resilience is available on npm and can be installed using any package manager: 
npm install @oldwhisper/resilience

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Requirements

  • Node.js: 16.x or higher
  • TypeScript: 5.x or higher (optional, but recommended)
Resilience is an ESM-only package. Make sure your project is configured to use ES modules.

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TypeScript setup

Resilience is written in TypeScript and includes type definitions out of the box. No additional setup is required. The library exports all type definitions you need: 
import type { 
  ResilienceConfig,
  BackoffStrategy,
  CircuitBreakerConfig,
  ResilienceHooks 
} from '@oldwhisper/resilience';

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Type definitions included

Resilience provides full TypeScript support with these key types:
  • ResilienceConfig - Configuration options for withResilience
  • BackoffStrategy - Fixed or exponential backoff configuration
  • CircuitBreakerConfig - Circuit breaker threshold and timeout settings
  • ResilienceHooks - Lifecycle hooks for observability
  • CircuitState - Circuit breaker state (CLOSED, OPEN, HALF_OPEN)

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ESM configuration

Since Resilience is an ESM package, ensure your package.json includes: 
{
  "type": "module"
}
If you’re using TypeScript, your tsconfig.json should have: 
{
  "compilerOptions": {
    "module": "ESNext",
    "moduleResolution": "node"
  }
}

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Verify installation

Create a simple test file to verify everything is working: 
import { withResilience } from '@oldwhisper/resilience';

const greet = withResilience(
  (name: string) => `Hello, ${name}!`,
  { 
    name: 'greet',
    retries: 1 
  }
);

const result = await greet('World');
console.log(result); // "Hello, World!"
Run the test: 
node test.js
If you see “Hello, World!” printed, your installation is successful!

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Bundle size

Resilience is lightweight and has zero dependencies:
  • Uncompressed: ~8 KB
  • Minified: ~3 KB
  • Gzipped: ~1.5 KB
This makes it perfect for:
  • Browser applications
  • Serverless functions (AWS Lambda, Cloudflare Workers, etc.)
  • Edge computing environments
  • Microservices where bundle size matters

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Environment support

Resilience works in any JavaScript environment that supports:
  • Promises and async/await
  • setTimeout and Date.now()
  • AbortController and AbortSignal (optional, for timeout cancellation)
Resilience uses AbortController for timeout cancellation when useAbortSignal is enabled. This feature requires an environment that supports the AbortController API (Node.js 15+, all modern browsers).

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Next steps

Quickstart

Get started with your first resilient function

Core concepts

Learn about retries, backoff, and circuit breakers

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