It's for sites like Google who want to know which search result you click on. Previously, this involved adding an on click handler to the link. The JavaScript i

It's for sites like Google who want to know which search result you click on. Previously, this involved adding an on click handler to the link. The JavaScript in the handler then delayed the navigation to the next page, as unloading the page would stop the JS&the ping request would not get sent. With this feature, the browser could immediately navigate to the link target and simultaneously make the ping request in the background.