holgerjust.de/source/javascripts/obfuscate.js

(function() {
  domready(function () {
    function decodeHTMLEntities(str) {
      if(str && typeof str === 'string') {
        var e = document.createElement('div');
        e.innerHTML = str;
        str = e.innerHTML;
        e.remove();
      }
      return str;
    }
    function encodeHTMLEntities(str) {
      var buf = [];
      for (var i=str.length-1;i>=0;i--) {
        buf.unshift(['&#', str[i].charCodeAt(), ';'].join(''));
      }
      return buf.join('');
    };

    (function() {
      var elements = document.getElementsByClassName("hidden-email");
      Array.prototype.forEach.call(elements, function(element){
        var encoded = element.getAttribute("data-email");
        var plain_encoded = decodeHTMLEntities(encoded)
        var plain_decoded = plain_encoded.replace(/[!-~]/g,function(c){
          return String.fromCharCode(126>=(c=c.charCodeAt(0)+47)?c:c-94);
        });
        var decoded = encodeHTMLEntities(plain_decoded);

        var link = "<" + "a h" + "ref=\"mai" + "lto:" + decoded + "\">" + decoded + "</" + "a>";
        element.innerHTML = link;
      });
    })();
  });
})();