Definition
HTML Standard defines EventSource
[Exposed=(Window,Worker)]
interface EventSource : EventTarget {
constructor(USVString url, optional EventSourceInit eventSourceInitDict = {});
readonly attribute USVString url;
readonly attribute boolean withCredentials;
// ready state
const unsigned short CONNECTING = 0;
const unsigned short OPEN = 1;
const unsigned short CLOSED = 2;
readonly attribute unsigned short readyState;
// networking
attribute EventHandler onopen;
attribute EventHandler onmessage;
attribute EventHandler onerror;
undefined close();
};