WTF Wikipedia anchors encoding

wtf_wikipedia_anchors.js

// Wikipedia link cleanup
(function (wpl) {
    if (wpl) {
        function decodeWikiURL(link) {
            function deChar(ss) {
                return decodeURIComponent(ss.replace(/\.([0-9A-F][0-9A-F])/g, '%$1'));
            }

            function deChar2(hhh) {
                var ch = deChar(hhh);
                return ('!"#$%&\'()*+,/;<=>?@\\^`~'.indexOf(ch) >= 0)
                     ? ch
                     : hhh;
            }
            
            // simplify internal link: replace %20 and _ then decode anchor
            link = link
                .replace(/(_|%20)/g, ' ')
                .replace(/^ +| +$/g, '')
                .replace('http://', '');

            var parts = link.split('#');
            
            // no anchor
            if (parts.length != 2) {
                return deChar(link);
            }
            
            var anchor = parts[1]
                .replace(
                    /\.F[0-4]\.[89AB][\dA-F]\.[89AB][\dA-F]\.[89AB][\dA-F]/g,
                    deChar)
                .replace(
                    /\.E[\dA-F]\.[89AB][\dA-F]\.[89AB][\dA-F]/g,
                    deChar)
                .replace(
                    /\.[CD][\dA-F]\.[89AB][\dA-F]/g,
                    deChar)
                .replace(
                    /\.[2-7][0-9A-F]/g,
                    deChar2);
            
            return (deChar(parts[0]) + ' : ' + anchor);
        }
        wpl.innerHTML = decodeWikiURL(wpl.href);
    }
})(id('wikipedia-article'));