The EventSource() constructor returns a newly-created EventSource, which represents a remote resource.


eventSource = new EventSource(url, configuration);


A USVString that represents the location of the remote resource serving the events/messages.
configuration Optional
Provides options to configure the new connection. The possible entries are:
  • withCredentials, defaulting to false, indicating if CORS should be set to include credentials.


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

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

  newElement.textContent = "message: " +;

Note: You can find a full example on GitHub — see Simple SSE demo using PHP.


Specification Status Comment
HTML Living Standard
The definition of 'EventSource()' in that specification.
Living Standard Initial definition

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support9 No6 No115
CORS support (withCredentials)26 No11 No12 ?
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidOpera AndroidiOS SafariSamsung Internet
Basic support918 No6115 ?
CORS support (withCredentials)2626 No1412 ? ?

See also

Document Tags and Contributors

Contributors to this page: fscholz, chrisdavidmills, carlos-lopez, zemlanin, teoli
Last updated by: fscholz,