FastEvent

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FastEvent is a well-designed, powerful, type-safe, and thoroughly tested event emitter that provides robust event subscription and publishing mechanisms, suitable for both nodejs/browser environments.

Installation

npm install fastevent
yarn add fastevent
pnpm add fastevent
bun add fastevent

Features

Core Event System

• 🚀 Flexible Triggering — Sync emit and async emitAsync (awaits all Promises), perfect for async listeners.
• 🎯 Hierarchical Event Paths — /-delimited routing (e.g. user/profile/update) keeps event structure clear and organized.
• 🌲 Tree-based Storage — An efficient tree structure for fast listener lookup and dispatch at scale.
• 🎭 Wildcard Matching — * (single level) and ** (multi level) for flexible subscriptions like user/* or user/**.
• 📡 Broadcast — Publish-side prefix broadcast wakes all descendant subscribers in a single emit.

Listener Management

• ⚡ Smart Registration — on, once, and onAny (global) listeners for any scenario.
• 🎨 Rich Options — count, prepend, filter, context, and more for fine-grained behavior control.
• 🔄 Listener Pipes — Wrap listeners with queue, throttle, debounce, timeout, retry, and memorize.
• 🧹 Automatic Cleanup — Native using keyword for scope-based subscriber teardown.
• ↩️ Return Value Collection — Listener return values gathered by emit/emitAsync in registration order.

Advanced Capabilities

• 🎪 Scopes — Namespace isolation that shares the parent listener table, with automatic prefix handling.
• 💾 Retained Messages — New subscribers instantly receive the last event value via retain.
• ⏳ waitFor — Promise-based event waiting with configurable timeout.
• 🔂 Async Iterators — Consume events naturally via for await...of.
• 🛑 Abortable Execution — Cooperative cancellation of async listeners with AbortSignal.
• 🎛 Metadata (meta) — Attach extra context at the global, scope, or event level.
• 🔁 Message Transform — Customize the message shape each listener receives.
• 🧭 Listener Context — Configure the this binding at instance, scope, or listener level.

Execution Control

• 🔌 Executors — Control how listeners run: parallel, race, series, waterfall, first, last, random, balance, or a custom function.
• 🎣 Lifecycle Hooks — Tap into onAddBeforeListener, onBeforeExecuteListener, onAfterExecuteListener, and more.
• 🛡 Robust Error Handling — Errors captured as results by default; opt in to throwing with ignoreErrors or customize via onListenerError.
• 🔗 Event Forwarding — Elegantly forward publish/subscribe across FastEvent instances.

Ecosystem

• 🚌 Event Bus — FastEventBus + FastEventBusNode for event-driven modular apps, supporting broadcast, publish/subscribe, and point-to-point messaging.
• 🪶 LiteEvent — A ~1/3 size variant (~2.3 KB gzipped) with the same core API and type experience, for bundle-size-sensitive scenarios.
• 🧬 Class Inheritance — Extend FastEvent / FastEventScope to customize options and behavior.
• 🔍 DevTools Viewer — Built-in fastevent-viewer component for visual debugging.

Type Safety & Quality

• 📝 Full TypeScript Support — Complete generics for events, payloads, and metadata.
• 🎯 Smart Type Inference — Listener parameter types auto-derived from event definitions.
• 🧪 Thoroughly Tested — 320+ test cases with 99%+ coverage.

License

MIT

For more detailed documentation, see WebSite