User:StevenJohnston/monobook.js

function externISBN { var magicURL = "http://unicorn.lib.ic.ac.uk/uhtbin/isbn/MAGICNUMBER"; var magicRegex = /MAGICNUMBER/ig; if(wgPageName != "Special:Booksources" && wgPageName != "Wikipedia:Book_sources"){ for (var i = 0; i < document.links.length; i++) { if( document.links[i].href.match(/isbn=(.*)/) ) { document.links[i].href=magicURL.replace(magicRegex, RegExp.$1); }   }  } } addOnloadHook(externISBN);