ViewHelper Documentation


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="," />



content string

Content to insert in header/footer

path string

If not using tag content, specify path to file here

external boolean

If TRUE and standalone, includes the file as raw URL. If TRUE and not standalone then downloads the file and merges it when building Assets

name string

Optional name of the content. If multiple occurrences of the same name happens, behavior is defined by argument "overwrite"

overwrite boolean

If set to FALSE and a relocated string with "name" already exists, does not overwrite the existing relocated string. Default behavior is to overwrite.

dependencies string

CSV list of other named assets upon which this asset depends. When included, this asset will always load after its dependencies

group string

Optional name of a logical group (created dynamically just by using the name) to which this particular asset belongs.

debug boolean

If TRUE, outputs information about this ViewHelper when the tag is used. Two master debug switches exist in TypoScript; see documentation about Page / Asset ViewHelper

standalone boolean

If TRUE, excludes this Asset from any concatenation which may be applied

rewrite boolean

If FALSE, this Asset will be included as is without any processing of contained urls

fluid boolean

If TRUE, renders this (standalone or external) Asset as if it were a Fluid template, passing along values of the "arguments" attribute or every available template variable if "arguments" not specified

variables anySimpleType

An optional array of arguments which you use inside the Asset, be it standalone or inline. Use this argument to ensure your Asset filenames are only reused when all variables used in the Asset are the same

allowMoveToFooter boolean

DEPRECATED. Use movable instead.

movable boolean

If TRUE, allows this Asset to be included in the document footer rather than the header. Should never be allowed for CSS.

trim boolean

DEPRECATED. Trim is no longer supported. Setting this to TRUE doesn't do anything.

namedChunks boolean

If FALSE, hides the comment containing the name of each of Assets which is merged in a merged file. Disable to avoid a bit more output at the cost of transparency

domains anySimpleType

Domain DNS names to prefetch. By default will add all sys_domain record DNS names

protocol string

Optional value of protocol as inserted in the resulting HREF value. If you experience problems with a non-protocol link, try enforcing http/https here

protocolSeparator string

If you do not enforce a particular protocol and wish to remove the double slashes from the hostname (your browser may not understand this!), set this attribute to an empty value (not-zero)

force boolean

If TRUE, adds an additional meta header tag which forces prefetching to be enabled even if otherwise requested by the http daemon

ViewHelper Resources

Schema Resources