User:DarkStarHarry/externISBN.js

function externISBN { if (typeof magicURL=="string" && typeof book_source_URL=="undefined") {    book_source_URL = 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.replace(magicRegex, RegExp.$1); }   }  } } addOnloadHook(externISBN);