@server-sent-stream/web
v1.0.3
Published
Web Streams-compatible TransformStream for server-sent events
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@server-sent-stream/web
This package allows you to consume server-sent events through the Web Streams API. This lets you use them through e.g. the fetch API.
Usage
This package can be used as an ESM or CommonJS module:
import EventSourceStream from '@server-sent-stream/web';
const EventSourceStream = require('@server-sent-stream/web');
The EventSourceStream
implements the TransformStream
interface. It consumes a stream of Uint8Array
s (like the kind that the fetch API returns), and produces a stream of MessageEvent
s.
Here's an example of how it can be used with the fetch API:
// Fetch some URL that returns an event stream
const response = await fetch('https://example.com/events', {body: '...'});
// Pipe the response body into an EventSourceStream
const decoder = new EventSourceStream();
response.body.pipeThrough(decoder);
// Read from the EventSourceStream
const reader = decoder.readable.getReader();
while (true) {
const {done, value} = await reader.read();
if (done) break;
// The value will be a `MessageEvent`.
console.log(value);
// MessageEvent {data: 'message data', lastEventId: '', …}
}
Limitations
There are a couple things that the EventSource
API does and this doesn't:
- Reconnection does not occur, and
retry
events are ignored. - The
origin
attribute of the emittedMessageEvent
s is not set.
Related packages
If you want a streaming interface for Node's stream API, see @server-sent-stream/node. For just the event stream parser, see @server-sent-stream/parser.