(function() {

  var weiredChar = String.fromCharCode(57344);

String.prototype.replaceAll = function(replace_what, replace_with) {

    var a = '';

    var b = this;

    do {

      a = b;

      b = a.replace(replace_what, weiredChar);

    } while (a !== b)

    do {

      a = b;

      b = a.replace(weiredChar, replace_with);

    } while (a !== b)

    return b;

};

})();

​

console.log("Hallo".replaceAll('l', '-ll-'));