sveltekit-eventsource - v1.0.0

@sourceregistry/sveltekit-eventsource

Typed Server-Sent Events (SSE) for SvelteKit with first-class TypeScript support, strongly typed client–server communication, and a versioned control protocol.

Overview

This library provides a structured, production-ready abstraction over native Server-Sent Events (SSE) for SvelteKit applications.

It focuses on:

Type safety via App.Events
Protocol-level control messages
Clean separation between application payloads and transport mechanics
Predictable lifecycle management

Getting Started

📦 Install the package
🖥 Set up a server-side SSE endpoint
🌐 Subscribe from the client with typed events

See:

module:client.EventSource | Client API
module:server.EventSource | Server API

Architecture

Typed Event Model

All application events are defined once using:

declare global {
  namespace App {
    interface Events {
      status: {
        heartbeat: number;
      };
    }
  }
}

This definition drives both:

server-side emit() typing
client-side on() typing

Control Protocol (SMCP)

This library implements a protocol-level control channel for SSE, known as:

SSE Magic Control Protocol (SMCP)

SMCP guarantees that critical control messages (such as server-requested close) remain decodable even if custom serializers/deserializers are used.

📄 Protocol specification: ➡️ {@page sse-magic-protocol}

API Documentation

{@link module:client | Client Module}
{@link module:server | Server Module}

Each module is fully documented using TSDoc.

Status

Protocol version: v1
Stability: Experimental (0.x)
Node.js: >= 16
Svelte: >= 5