A streaming parser for server-sent events/eventsource, without any assumptions about how the actual stream of data is retrieved. It is intended to be a building block for clients and polyfills in javascript environments such as browsers, node.js and deno.
If you are looking for a modern client implementation, see eventsource-client.
You create an instance of the parser, and feed it chunks of data - partial or complete, and the parse emits parsed messages once it receives a complete message. A TransformStream variant is also available for environments that support it (modern browsers, Node 18 and higher).
npm install --save eventsource-parserimport {createParser, type ParsedEvent, type ReconnectInterval} from 'eventsource-parser'
function onParse(event: ParsedEvent | ReconnectInterval) {
if (event.type === 'event') {
console.log('Received event!')
console.log('id: %s', event.id || '<none>')
console.log('name: %s', event.name || '<none>')
console.log('data: %s', event.data)
} else if (event.type === 'reconnect-interval') {
console.log('We should set reconnect interval to %d milliseconds', event.value)
}
}
const parser = createParser(onParse)
const sseStream = getSomeReadableStream()
for await (const chunk of sseStream) {
parser.feed(chunk)
}
// If you want to re-use the parser for a new stream of events, make sure to reset it!
parser.reset()
console.log('Done!')import {EventSourceParserStream} from 'eventsource-parser/stream'
const eventStream = response.body
.pipeThrough(new TextDecoderStream())
.pipeThrough(new EventSourceParserStream())Note that the TransformStream is exposed under a separate export (eventsource-parser/stream), in order to maximize compatibility with environments that do not have the TransformStream constructor available.
MIT © Espen Hovlandsdal