ssestream
Version:
Send Server-Sent Events with a stream
64 lines • 2.24 kB
JavaScript
;
Object.defineProperty(exports, "__esModule", { value: true });
const stream_1 = require("stream");
function dataString(data) {
if (typeof data === 'object')
return dataString(JSON.stringify(data));
return data.split(/\r\n|\r|\n/).map(line => `data: ${line}\n`).join('');
}
/**
* Transforms "messages" to W3C event stream content.
* See https://html.spec.whatwg.org/multipage/server-sent-events.html
* A message is an object with one or more of the following properties:
* - data (String or object, which gets turned into JSON)
* - event
* - id
* - retry
* - comment
*
* If constructed with a HTTP Request, it will optimise the socket for streaming.
* If this stream is piped to an HTTP Response, it will set appropriate headers.
*/
class SseStream extends stream_1.Transform {
constructor(req) {
super({ objectMode: true });
if (req) {
req.socket.setKeepAlive(true);
req.socket.setNoDelay(true);
req.socket.setTimeout(0);
}
}
pipe(destination, options) {
if (destination.writeHead) {
destination.writeHead(200, {
'Content-Type': 'text/event-stream; charset=utf-8',
'Transfer-Encoding': 'identity',
'Cache-Control': 'no-cache',
Connection: 'keep-alive',
});
destination.flushHeaders();
}
// Some clients (Safari) don't trigger onopen until the first frame is received.
destination.write(':ok\n\n');
return super.pipe(destination, options);
}
_transform(message, encoding, callback) {
if (message.comment)
this.push(`: ${message.comment}\n`);
if (message.event)
this.push(`event: ${message.event}\n`);
if (message.id)
this.push(`id: ${message.id}\n`);
if (message.retry)
this.push(`retry: ${message.retry}\n`);
if (message.data)
this.push(dataString(message.data));
this.push('\n');
callback();
}
writeMessage(message, encoding, cb) {
return this.write(message, encoding, cb);
}
}
exports.default = SseStream;
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