The ping attribute of the a element is used for hyperlink auditing - basically when a link is followed each url listed in the attribute is 'pinged' with a HTTP POST.
According to Can I Use it's supported on all major modern browsers except Firefox (one day maybe).
How do I detect with JavaScript if the browser supports this functionality?
The following expression "ping" in HTMLAnchorElement.prototype will return true if the browser supports the ping attribute, false otherwise.