Before we start writing a page-mode, we need to cover an important utility function that gets much use in page-modes called build_url_regexp. Part of writing a page-mode is constructing a test against which an url can be matched so that Conkeror knows when to turn the page-mode on. The test can actually be either a function or a regular expression, but regular expressions are the more commonly used.
Regular expressions to match urls can be complex, so to help, we use the utility function build_url_regexp to create them. It takes several keyword arguments that specify parts of an url, and produces a regexp accordingly.
A regexp or a literal string to match the domain name, not including the top-level domain (.com, .net, .org, etc), and not including www., unless the www. is required.
Boolean where true means that the domain name may optionally have the subdomain www.. Default is false.
A list of allowed top-level domains. The default is the list ["com"].
A regexp or a literal string to match against the path portion of the url, excluding the initial /. The default matches any path.