Question

Using JavaScript I would like to check if a given URL matches a list of URL schemes. I have come this far:

function on_wikipedia() {
    // the list of allowed locations
    var allowed_locations = new Array( "http://*.wikibooks.org/*"
                                     , "http://*.wikimedia.org/*"
                                     , "http://*.wikipedia.org/*"
                                     , "http://*.wikiquote.org/*"
                                     , "http://*.wikiversity.org/*"
                                     , "http://*.wiktionary.org/*"
                                     , "http://www.mediawiki.org/*"
                                     , "https://secure.wikimedia.org/*"
                                     );

    // current location; e.g. "http://en.wikipedia.org/wiki/Main_Page"
    var current_location = content.document.location;

    var valid = false;

    // compare current_location to allowed_locations and set valid to true,
    // if it matches
    //
    // FIXME

    return valid;
}

Maybe it is a bad idea to do it like this. Maybe I should use regular expressions to make the comparason? Unfortunately I’m lost… I have no JavaScript experience at all. Could someone please point me in the right direction?

Answer 1

function onWikipedia(){
  // Untested
  var allowedLocations = /^(?:http:\/\/(?:.+?\.wik(?:ibooks|imedia|ipedia|iquote|iversity|tionary)\.org|www\.mediawiki\.org)\/|https:\/\/secure.wikimedia.org\/)/i;
  return allowedLocations.test( content.document.location );
} 

The i at the end of the regex makes it case-insensitive. Remove if you don’t want that.

In general, the regex says this:

• Starting at the front of the string (^), look for either of the following ((?:...|...)):
  • http:// followed by either of the following, and then a literal slash (\/)
    • basically anything (.+?) followed by a literal period (\.) followed by wik and then…oh, one of these domain names, followed by .org, or
    • www.mediawiki.org
  • https://secure.wikimedia.org/

Note that the very permissive .+? allows something like http://foo.bar.com/?.wikibooks.org/ to be matched. You probably want something more restrictive, such as letters, numbers, underscores, periods, or hyphens. If so, replace .+? with [\w.-]+?

Alternatively, instead of testing against the entire URL, you might want to just check against the hostname:

function onWikipedia(){
  if (location.protocol=='https:'){
    return location.hostname == 'secure.wikimedia.org';
  }else{
    var regexp = /^(?:www\.wikimedia|.+?\.wik(?:ibooks|imedia|ipedia|iquote|iversity|tionary)\.org/i;
    return regexp.test( location.hostname );
  }
}