Creates a new EventSource. The connection attempt starts before this function returns, so a
caller must attach any listener it needs (onopen, onerror, addEventListener, ...) right
after this call, before any other code runs, to avoid missing an event.
Creates a new EventSource. The connection attempt starts before this function returns, so a caller must attach any listener it needs (
onopen,onerror,addEventListener, ...) right after this call, before any other code runs, to avoid missing an event.