User:Lunchboxhero/externISBN.js

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Documentation for this user script can be added at User:Lunchboxhero/externISBN.

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function externISBN() {
  if (typeof magicURL=="string")
  { 
    var book_source_URL_test = magicURL; 
  }

  var magicRegex = /MAGICNUMBER/ig;
  if(wgPageName != "Special:BookSources" && !(wgTitle == "Book sources" && wgCanonicalNamespace == "Project"))
  {
    for (var i = 0; i < document.links.length; i++) 
    {       
      if(document.links[i].href.match(/Special:BookSources\/(.*)/)) 
      {
        document.links[i].href=book_source_URL_test.replace(magicRegex, RegExp.$1);
      }
    }
  }

}

addOnloadHook(externISBN);