HTML5 Server-Sent Events: How to set withCredentials option?

Question

According to WHATWG - Server-Sent Events below is the API for using EventSource interface:

[Constructor(DOMString url, optional EventSourceInit eventSourceInitDict)]
interface EventSource : EventTarget {
  readonly attribute DOMString url;
  readonly attribute boolean withCredentials;
  //....
};

The withCredentials attribute must return the value to which it was last initialized. When the object is created, it must be initialized to false.

Simple example:

var stocks = new EventSource("events.php");
stocks.onmessage = function (event) {
  //alert(event.data);
};

Now, how to include or set withCredentials in this example?

Answer 1

I've not tried it, but going by the spec you link to, I believe it would be like this:

var stocks = new EventSource("events.php", { withCredentials: true });

If you go to http://www.w3.org/TR/WebIDL/#idl-exceptions then scroll up to see the example immediately above that, you can see a similar pattern of using a dictionary to set initialization values.