asset.prefetch ViewHelper <vhs:asset.prefetch>

Asset DNS Prefetching ViewHelper

Enables the special <link rel="dns-prefetch" /> tag which instructs the browser to start prefetching DNS records for every domain listed in the domains attribute of this ViewHelper. Prefetching starts as soon as the browser becomes aware of the tag - to optimise even further, you may wish to control the output buffer's size to deliver your site HTML in chunks, the first chunk being the one containing this ViewHelper.

Note that the web server daemon may send headers which prevent this prefetching and that these headers can be added in many ways. If prefetching does not work, you will need to inspect the HTTP headers returned from the actual environment. Or you may prefer to simply add force="TRUE" to this tag - but beware that this will affect the entire document's behaviour, not just for this particular set of domain prefetches. Once force-enabled this setting cannot be disabled (unless done so by manually adding an additional meta header tag as examplified by the build() method.

Example usage:

<v:asset.prefetch domains="fedext.net,ajax.google.com" />

See: https://developer.mozilla.org/en-US/docs/Controlling_DNS_prefetching

Arguments