Most browsers logs the URLs a user has visited. This history is taken care of in a period which in many cases, the user can decide the length of. This can in many ways be practical for the user, especially when entering URLs in the address field. If you have visited the site before, your readers may fill out the rest of the URL once the user has entered the first part.
But the content of Web pages can be influenced by history. Links to web pages you have visited before, is often shown with a different color or style than non-visited links. How do the links look like, can be determined using a stylesheet (CSS).
The problem in most browsers is that the information about whether the links have been visited or not, is available via the Web site that links are displayed. Such information can be gathered using the JavaScript functions that getComputedStyle ().
Challenges is that you can not simply turn off this option without the users lose function.
Mozilla has been clear over the issue since 2002, when a notice was posted to Bugzilla.
Only now it appears that Mozilla has come up with a solution. In a blog post writes Sid tribes in Mozilla Security that by using three different measures will solve the problem. One is that it greatly restricts the types of styles that can be used to distinguish visited links from other links. In practice this means that only the different colors (foreground, background, outline, borders, etc) that hereafter may be different from the non-visited links. Other types of styles will be ignored.
Tribal writes that this is a violation of the CSS 2.0 specification, but CSS 2.1 addressing the problem.
In addition, Mozilla change certain properties in the presentation engine to minimize the differences in layout time for visiting and non-visited links, and reduce access a website has the calculated style of a link. In practice it means that Firefox in connection with the JavaScript functions will always be the style values for the non-visited links, regardless of whether the links have been visited or not.
Tribal writes that he hopes that the other browser vendors will now follow suit, since this is not a problem that only applies to Firefox.
For users, the change means that the visited links will be able to see something different on sites that use other than color differences to distinguish between visited and non-visited links. In some cases it may happen that it will be possible to distinguish such links before the site has introduced the second differences in styles. But there are also many sites where visited and non-visited links appear different.
