The EventTarget.addEventListener() method registers the specified listener on the EventTarget it's called on.
The close() method must abort any instances of the fetch algorithm started for this EventSource object, and must set the readyState attribute to CLOSED.
Dispatches an Event at the specified EventTarget, invoking the affected EventListeners in the appropriate order.
The readyState attribute represents the state of the connection.
Removes the event listener previously registered with EventTarget.addEventListener.
The url attribute must return the absolute URL that resulted from resolving the value that was passed to the constructor.
The withCredentials attribute must return the value to which it was last initialized.