HTML5 Server-Sent Events allow a web page to get updates from a server.
A server-sent event is when a web page automatically gets updates from a server.
This was also possible before, but the web page would have to ask if any updates were available. With server-sent events, the updates come automatically.
Examples: Facebook/Twitter updates, stock price updates, news feeds, sport results, etc.
Server-Sent Events are supported in all major browsers, except Internet Explorer.
The EventSource object is used to receive server-sent event notifications:
In the tryit example above there were some extra lines of code to check browser support for server-sent events:
For the example above to work, you need a server capable of sending data updates (like PHP or ASP).
The server-side event stream syntax is simple. Set the "Content-Type" header to "text/event-stream". Now you can start sending event streams.
Code in PHP (demo_sse.php):
Code in ASP (VB) (demo_sse.asp):
In the examples above we used the onmessage event to get messages. But other events are also available:
|onopen||When a connection to the server is opened|
|onmessage||When a message is received|
|onerror||When an error occurs|
The perfect solution for professionals who need to balance work, family, and career building.
More than 10 000 certificates already issued!
The HTML Certificate documents your knowledge of HTML.
The HTML5 Certificate documents your knowledge of advanced HTML5.
The CSS Certificate documents your knowledge of advanced CSS.
The jQuery Certificate documents your knowledge of jQuery.
The XML Certificate documents your knowledge of XML, XML DOM and XSLT.
The ASP Certificate documents your knowledge of ASP, SQL, and ADO.
The PHP Certificate documents your knowledge of PHP and SQL (MySQL).
Your message has been sent to W3Schools.