Traditionally, a web page has to send a request to the server to receive new data; that is, the page requests data from the server. With server-sent events, it's possible for a server to send new data to a web page at any time, by pushing messages to the web page. These incoming messages can be treated as Events + data inside the web page.




See also


Specification Status Comment
Server-Sent Events Recommendation Initial definition.

Browser compatibility

Feature Chrome Edge Firefox (Gecko) Internet Explorer Opera Safari
EventSource support 6 No support 6.0 (6.0) [1] No support 9 [2] 5
Feature Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
EventSource support 4.4 45 ? 12 4.1

[1] Firefox currently does not support EventSource in web/shared workers. and prior to version 36 server-sent events do not reconnect automatically in case of a connection interrupt.

[2] Opera 9 partial supports Server-sent Events.

Document Tags and Contributors

 Last updated by: valtlai,