The ping
attribute was included in pre-W3C drafts of HTML5. It remained in W3C drafts of HTML5 up until early 2010 - the last draft to include it was W3C Working Draft 4 March 2010; the next draft was W3C Working Draft 24 June 2010.
Why was it removed? It was massively unpopular - an HTML feature designed for advertisers to track clicks on adverts. Hixie's argument was that they can already do that; ping
just made the process more transparent. And browsers would be able to offer a feature to block ping
tracking. The counter-argument to that is that if browsers had this feature, publishers would avoid ping
, it being unreliable compared to current click-tracking techniques.
Some browsers support it because of a combination of:
Browsers that support it seem to be Safari and Chrome. (It's no surprise that the latter does; it originally used Safari's WebKit as its layout engine, and now uses Blink, a fork of WebKit.) Firefox also supports it, but since 2008, support has been disabled by default - it can be enabled through about:config, though I don't suppose many people do.
Internet Explorer does not support it (yet?). Opera 12.x does not support the attribute, but I haven't checked in Opera's next generation of Blink-based browsers.