Server-Sent Events (SSE) client for Node.js and browsers with automatic reconnection.

npm install @neabyte/sse-client

<script type="module">
  import sseClient from 'https://cdn.jsdelivr.net/npm/@neabyte/sse-client/+esm'

  const client = sseClient('https://api.example.com/events', (message) => {
    console.log('SSE Response:', message)
  })
</script>

// ESM
import sseClient from '@neabyte/sse-client'

 // CommonJS
const sseClient = require('@neabyte/sse-client')

// Simple connection with message callback
const client = sseClient('https://api.example.com/events', (message) => {
  console.log('SSE Response:', message)
})

import sseClient, { type SSEConfig, SSEClient } from '@neabyte/sse-client'

// Configuration with custom settings
const config: SSEConfig = {
  headers: {
    'Authorization': 'Bearer your-token',
    'X-Custom-Header': 'value'
  },
  retryInterval: 5000,    // Retry every 5 seconds (default: 3000)
  retryAttempts: 10,      // Try up to 10 times (default: 3)
  autoReconnect: true,    // Enable auto-reconnection (default: true)
  timeout: 30000          // 30 second connection timeout (default: 30000)
}

// Create client with configuration
const client: SSEClient = sseClient('https://api.example.com/events', (message: unknown) => {
  console.log('SSE Response', message)
}, config)

// Listen for connection status changes
client.on('callback', (data) => {
  console.log('SSE Callback:', data)
})

sseClient(url, callback, config?)

• url <string>: The SSE endpoint URL to connect to.
• callback <function>: Function to handle incoming messages.
  • message <SSEMessage>: The received SSE message object.
• config <SSEConfig>: (Optional) Configuration options for the client.
  • headers <Record<string, string>>: (Optional) Custom headers to send with the request.
  • retryInterval <number>: (Optional) Retry interval in milliseconds. Defaults to 3000.
  • retryAttempts <number>: (Optional) Maximum number of retry attempts. Defaults to 3.
  • autoReconnect <boolean>: (Optional) Enable automatic reconnection. Defaults to true.
  • timeout <number>: (Optional) Connection timeout in milliseconds. Defaults to 30000.
• Returns: SSEClient
• Description: Factory function that creates and connects an SSE client with automatic reconnection.

client.connect()

• Returns: Promise<void>
• Description: Establishes connection to the SSE endpoint with retry logic and error handling.

client.disconnect()

• Returns: void
• Description: Disconnects from the SSE endpoint and cleans up resources.

client.on('callback', (status) => {})

• status <object>: Connection status information.
  • name <ConnectionStatus>: Current connection status. Possible values:
    • 'connecting' - Initial connection attempt
    • 'connected' - Successfully connected and streaming
    • 'disconnected' - Connection closed (normal or error)
    • 'reconnecting' - Attempting to reconnect after failure
    • 'error' - Connection failed with error
  • message <string | null>: Optional status message.
• Description: Emitted when connection status changes.

This project is licensed under the MIT License - see the LICENSE file for details.