Using Event Emitter

Events

The Ratelimit instance and the RateLimitBuilder (registry) are EventEmitters.

Ratelimit Instance Events:

• error: Emitted when an operational error occurs (e.g., Redis issue). Passes the error object.
• allowed: Emitted when a .limit() call succeeds. Passes { identifier, remaining, limit }.
• limited: Emitted when a .limit() call fails due to rate limiting. Passes { identifier, remaining, limit }.
• failOpen: Emitted when Redis fails but failOpen: true allows the request. Passes { identifier, error }.
• waiting: Emitted by block() on each retry attempt. Passes { identifier, attempt, waitTime, elapsed }.
• reset: Emitted when .reset() successfully clears a limit. Passes { identifier }.

Registry (RateLimitBuilder) Events:

• redisConnect: Emitted when a managed Redis client connects successfully. Passes { clientKey }.
• redisError: Emitted when a managed Redis client encounters an error. Passes { clientKey, error }.
• limiterRegister: Emitted when a limiter instance is successfully created and registered. Passes { name, clientKey }.
• limiterError: Emitted when registering or initializing a limiter fails. Passes { name, error }.
• close: Emitted when the registry's close() method is called.

import { rateLimiterRegistry } from '@/lib/ratelimit';
 
rateLimiterRegistry.on('redisError', ({ clientKey, error }) => {
  // Log Redis errors centrally, maybe send to monitoring
  console.error(`[Registry] Redis Client Error (${clientKey}):`, error);
});
 
rateLimiterRegistry.on('limiterError', ({ name, error }) => {
   console.error(`[Registry] Limiter Init Error (${name}):`, error);
});