EventSourceExtra.js

EventSourceExtra.js is a Javascript EventSource replacement designed to consume Server-Sent Events (SSE) streams with more options than the standard EventSource.
The main limitation of EventSource are:

• does not support POST DELETE PATCH requests
• no payload can be added to the request
• custom headers can not be added to requests

This package is designed to provide a usable replacement to EventSource that makes all of this possible: EventSourceExtra. It is a fully compatible EventSource polyfill so you should be able to:

EventSource = EventSourceExtra;

Basic usage

Installation:

npm install eventsource-extra
# or
git clone https://github.com/delcon/eventsource-extra .

The most simple way to use EventSourceExtra is to use it as documented as an EventSource replacement.

Create the EventSourceExtra object, attach one or more listeners, and activate the stream:

var source = new EventSourceExtra(url);

// subscribe by addEventListener:
source.addEventListener('message', function(e) {
  console.log(e);
});

source.stream();

For Documentation refer to: , documented here:
https://developer.mozilla.org/en-US/docs/Web/API/EventSource

Extra API

In addition to the standard API you have the following functions and apis:

Events

EventSourceExtra implements the EventTarget interface (just like EventSource) and emits fully constructed Event objects. The type of the event corresponds to the Server-Sent Event's name.

The sse events have the following fields:

• event: the event type, default is message
• id: the event ID, if present; null otherwise
• data: the event data, unparsed

In addition to Server-Sent EventsEventSourceExtra, will emit the following events:

• open, when the first block of data is received from the event stream;
• error, if an error occurs while making the request;
• readystatechange, to notify of a change in the ready state of the event source.

Additional Extra Event Features by EventSourceExtra:

• Subscribe by source.on('eventname', function(data){ ... }) to receive data only instead of the whole event
• Subscribe by source.on('data', function(data){ ... }) to receive all default events / messages
• If you subscribe by source.on(<eventname>, ... ) the data will be JSON - parsed if sent as JSON.
• Debug events by providing options.debug = true to see all Server-Sent and EventSourceExtra events logged to console. This is very useful for development.

Example: listening for specific event types

var source = new EventSourceExtra(url);

// subscribe by addEventListener:
source.addEventListener('status', function(e) {
  console.log('System status is now: ' + e.data);
});

// subscribe by on<eventname>:
source.onstatus = function(e) { 
  console.log('System status is now: ' + e.data);
};

// subscribe to data only (parsed):
source.on('status', function(data){
  console.log('System status is now: ' + data);
});

source.stream();

Sendig request

There are different ways to send requests:

• use the EventSource api: const sse = new EventSourceExtra(url, options ); sse.stram()
• use the added extra fetch api: const sse = new EventSourceExtra(); sse.fetch(url, options )

Request options

The options used in the constructor new EventSourceExtra(url, options )or used by calling sse.fetch(url, 'options') behave the same.

const options = {
  method: 'POST', // optional, GET POST PATCH DELETE, default is GET
  headers: {'Authorization': 'Bearer secret-key'}, // optional
  payload: '{ "foo" : "bar" }', // optional, String, FromData, Buffer ...
  withCredentials: true, // optional, default is false
  debug: true // optional, default is false
}

Options reference

| Name | Description | | ----------------- | ----------- | | headers | A map of additional headers to use on the HTTP request | | method | Override HTTP method (defaults to GET, unless a payload is given, in which case it defaults to POST) | | payload | An optional request payload to sent with the request | | withCredentials | If set to true, CORS requests will be set to include credentials | | debug | If set to true, all events will be logged to console |

Examples

• cd to examples/express, npm install then node index.js to run express

Credits

Credits to https://github.com/mpetazzoni/sse.js, this work is an extension and partially rewrite of his library.