sse-stringify

Marshalling Javascript data into Server-Sent Events (sse) text/event-stream format

Installing

``
npm install sse-stringify
`

Basic usage

`ts
import { sseStringify } from 'sse-stringify';

sseStringify({
id: '0',
data: JSON.stringify({}),
event: 'my-event',
});
// 'id: 0\nevent: my-event\ndata: {}\n\n'

sseStringify({ retry: 1000 });
// 'retry: 1000\n\n'

sseStringify({ comment: 'OK' });
// ': OK\n\n'
`

$3

It can be useful to send some lines of csv or ndjson within the same event/message.

`ts
const prettyJSON = JSON.stringify({ a: 1, o: { nested: [] } }, null, 2);
sseStringify({ data: prettyJSON });
/*
'data: {\n' +
'data: "a": 1,\n' +
'data: "o": {\n' +
'data: "nested": []\n' +
'data: }\n' +
'data: }\n' +
'\n'
*/
`

$3

We can pass false as the second parameter to disable the newline at the end and thus
call the function several times but send only 1 event with the result.

This allows better mapping between the JS data structure and the text/event-stream format or
use this function with iterables and streams.

`ts
let event = '';

const arr = [
{ event: 'my-event' },
{ data: 'csv or ndjson line' },
{ data: 'csv or ndjson line' },
{ id: '0' },
];

arr.forEach((value, index, array) => {
if (index === array.length - 1) {
// last item should have a newline at the end
event += sseStringify(value);
} else {
event += sseStringify(value, false);
}
});

/* or

arr.forEach((value, index, array) => {
event += sseStringify(value, false);
});

event += '\n';
*/

console.log(event);
// 'event: my-event\ndata: csv or ndjson line\ndata: csv or ndjson line\nid: 0\n\n'
``

$3

MIT licensed.