Valid XHTML 1.0!


Since Mozilla release 1.2 (and the Mozilla 1.2 based Phoenix 0.4 and higher too) that browser can preload other files, especially HTML files and pictures, while watching a page with some special prefetch tags on it. This can considerable shorten waiting for new stuff to load, because it is already loaded during watching the current page: when you are choosing to go there, it can be already in the browser cache. Only rendering remains now for the browser. It is the responsibility of us webmasters, to make helpful use of this feature.

While it is no security concern, I would consider it as privacy violation, to send you to other sites with this technique (there is no technical difference to regular visiting): I would suppose your will to change to a different site! I have no right to do so, therefore my policy is: I let prefetch only own contents. This kind of abuse sending people to other sites without their consent is fairly widespread in JavaScript code commonly found in the web, by the way!

And I try my best to limit it to obvious cases, where it is very likely, that you will follow a link (for example a multi-HTML-page topic in a straight thread).

But if you are really concerned by preloading contents you have not chosen or have very hard constraints on traffic, you may consider to disable it. From the following hint can be applied:

First finish Mozilla 1.2 or higher. Then open the file prefs.js in your local Mozilla configuration directory and add the line user_pref("network.prefetch-next", false); to your preferences file. After launching Mozilla again, prefetching of web contents is disabled. (this should work with Phoenix 0.4 and higher too)

I have no idea, if there is any other browser out there already supporting silent prefetching of link'd documents, so I propose to RTFM them, if unsure. My tests on 1. Dec 2002 revealed no others besides Mozilla 1.2, Phoenix 0.4 and maybe Galeon since 1.2.6, if compiled on top of Mozilla 1.2 (?). For example I would expect Opera to implement it in Opera 7 earlier or later; but this is just speculation (I have seen this request on their wishlist). The other Gecko engine browsers are likely to prefetch too in future releases, but this is partly the decision of their maintainers of course, if it is supported and if they offer a GUI switch for turning off (or on if default is off).

(additional remark: interesting enough the text browsers links and lynx are the only browsers at all, which display such a link element in the page: they treat it essentially like a href element; links displays both types (next and prefetch) of rel attributes with HTML and images, while lynx seems to be limited on next and HTML).

Final remark: the link element with the mentioned attribute values is part of HTML since version 2.0 (!). But Netscape and MSIE ignore these to this very day, despite it was always defined, in HTML 3.2, 4.0, XHTML 1, ...


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