Web/API/EventSource/open event

The open event of the EventSource API is fired when a connection with an event source is opened.

Bubbles	No
Cancelable	No
Interface	Event
Event handler property	EventSource.onopen

Examples

var evtSource = new EventSource('sse.php');

// addEventListener version
evtSource.addEventListener('open', (e) => {
  console.log("The connection has been established.");
});

// onopen version
evtSource.onopen = (e) => {
  console.log("The connection has been established.");
};

Specifications

Specification	Status
HTML Living StandardThe definition of 'open event' in that specification.	Living Standard

Browser compatibility

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
open event	Chrome Full support 6	Edge Full support 79	Firefox Full support 6	IE No support No	Opera Full support Yes	Safari Full support 5	WebView Android Full support Yes	Chrome Android Full support 18	Firefox Android Full support 45	Opera Android Full support 12	Safari iOS Full support 5	Samsung Internet Android Full support 1.0

Legend

Full support  

Full support

No support  

No support

See also

• Using server-sent events
• open
• error
• message

EventSource: open event by Mozilla Contributors is licensed under CC-BY-SA 2.5.