phpjs/functions/url/rawurldecode.js

php.js offers community built php functions in javascript

function rawurldecode(str) {
  //       discuss at: http://phpjs.org/functions/rawurldecode/
  //      original by: Brett Zamir (http://brett-zamir.me)
  //         input by: travc
  //         input by: Brett Zamir (http://brett-zamir.me)
  //         input by: Ratheous
  //         input by: lovio
  //      bugfixed by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
  // reimplemented by: Brett Zamir (http://brett-zamir.me)
  //      improved by: Brett Zamir (http://brett-zamir.me)
  //             note: Please be aware that this function expects to decode from UTF-8 encoded strings, as found on
  //             note: pages served as UTF-8
  //        example 1: rawurldecode('Kevin+van+Zonneveld%21');
  //        returns 1: 'Kevin+van+Zonneveld!'
  //        example 2: rawurldecode('http%3A%2F%2Fkevin.vanzonneveld.net%2F');
  //        returns 2: 'http://kevin.vanzonneveld.net/'
  //        example 3: rawurldecode('http%3A%2F%2Fwww.google.nl%2Fsearch%3Fq%3Dphp.js%26ie%3Dutf-8%26oe%3Dutf-8%26aq%3Dt%26rls%3Dcom.ubuntu%3Aen-US%3Aunofficial%26client%3Dfirefox-a');
  //        returns 3: 'http://www.google.nl/search?q=php.js&ie=utf-8&oe=utf-8&aq=t&rls=com.ubuntu:en-US:unofficial&client=firefox-a'

  return decodeURIComponent((str + '')
    .replace(/%(?![\da-f]{2})/gi, function() {
      // PHP tolerates poorly formed escape sequences
      return '%25';
    }));
}