@andyfischer/fetch-sse-stream

HTTP client using fetch with Server-Sent Events (SSE) parsing.

One fetch call will return a Stream object from @andyfischer/streams.

Installation

npm install @andyfischer/fetch-sse-stream

Usage

Basic Usage

import { fetchStream } from '@andyfischer/fetch-sse-stream';
import { c_item, c_fail, c_done } from '@andyfischer/streams';

const stream = fetchStream<ResponseType>('https://example.com/events');

// Process events as they arrive
stream.pipe(evt => {
    switch (evt.t) {
    case c_item:
        const item: ResponseType = evt.item;
        // ...
        break;
    case c_fail:
        // ...
        break;
    case c_done:
        // ...
        break;
    }
});

Advanced Usage

Set custom headers in the request.

import { fetchStream } from '@andyfischer/fetch-sse-stream';

const stream = fetchStream('https://example.com/events', {
    headers: {
        'Authorization': 'Bearer your-token'
    },
    onOpen: () => console.log('Connected'),
    onError: (error) => console.error('Connection error:', error)
});

// Process the stream
stream.pipe(evt => {
    // Handle events...
});

Using a Custom Fetch Function

You can provide your own fetch implementation (useful for testing, proxies, or custom authentication):

import { fetchStream } from '@andyfischer/fetch-sse-stream';
import nodeFetch from 'node-fetch';

const stream = fetchStream('https://example.com/events', {
    fetch: nodeFetch as any, // Use node-fetch instead of built-in fetch
    headers: {
        'User-Agent': 'MyApp/1.0'
    }
});

API

fetchStream(url, options?)

Creates and connects to an SSE stream immediately.

• url: The endpoint URL
• options: Optional configuration (extends RequestInit)

Returns a Stream<SSEEventData> from @andyfischer/streams.

FetchSSEStream

Class for more control over the connection lifecycle.

Constructor Options

• onOpen: Callback when connection opens
• onError: Callback for connection errors
• fetch: Custom fetch function to use instead of global fetch
• Plus all standard RequestInit options (headers, method, etc.)

Methods

• connect(): Start the connection and return the Stream
• close(): Close the connection and cleanup resources