julienmachon / sse-client

Server-sent event client using the fetch API

Why | Status | Development | License

Server-sent Event Client

This is a client for subscribing server-sent events using the fetch API.

Why not use EventSource?

Well, I only have one problem with EventSource and that's quite a biggy: You can't specify headers!

This is a major issue for me every time I have to use SSE mainly because I can't sent a bearer token or the last-event-id, as specified by the SSE spec.

After some quick research, I've found this issue. Based on the conversation, it looks like we'll never be able to set header using EventSource and that the fetch API combine with ReadableStream is a much better option.

I've not be able to find a single example or library, so I'm writing my own.

Status

In development

Documentation

import SSEClient from 'sse-client';

const es = new SSEClient('http://url', {
  headers: new Headers({
    'Last-Event-ID': 'some-id',
    Authorization: 'Bearer 123token',
  }),
});

es.onopen = (event: Event) => void;
es.onclose = () => void;
es.onmessage = (messageEvent: MessageEvent) => any;
es.addEventListener('MyEvent', (messageEvent) => any);
es.removeEventListener('MyEvent');
es.close();

Development

With Node.js

• Install: npm install
• Build: npm run build
• Test: npm run test
• Lint: npm run lint
• Generate Documentation: npm run documentation

With Docker

Make sure you have already installed both Docker Engine and Docker Compose.

• Install: make install
• Build: make build
• Test: make test
• Lint: make lint

License

• Apache License, Version 2.0