EventSource: message event

The message event of the EventSource API is fired when data is received through an event source.

Bubbles No
Cancelable No
Interface MessageEvent
Event handler property EventSource.onmessage


In this basic example, an EventSource is created to receive events from the server; a page with the name sse.php is responsible for generating the events.

var evtSource = new EventSource('sse.php');
var eventList = document.querySelector('ul');

evtSource.addEventListener('message', (e) => {
  var newElement = document.createElement("li");

  newElement.textContent = "message: " +;

onmessage equivalent

evtSource.onmessage = (e) => {
  var newElement = document.createElement("li");

  newElement.textContent = "message: " +;


Specification Status
HTML Living Standard
The definition of 'message event' in that specification.
Living Standard

Browser compatibility

Update compatibility data on GitHub
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
message eventChrome Full support 6Edge Full support 79Firefox Full support 6IE No support NoOpera Full support YesSafari Full support 5WebView Android Full support YesChrome Android Full support 18Firefox Android Full support 45Opera Android Full support 12Safari iOS Full support 5Samsung Internet Android Full support 1.0


Full support  
Full support
No support  
No support

See also