JS cookies

var writeCookie = function(name, value, days) {
  var expires = "";

  if (days) {
    var date = new Date();
    date.setTime(date.getTime() + (days * 24 * 60 * 60 * 1000));
    expires = "; expires=" + date.toGMTString();
  }

  document.cookie = name + '=' + value + expires + '; path=/';
}

var readCookie = function(name) {
  var searchName = name + '=';
  var cookies = document.cookie.split(';');

  for (var i = 0; i < cookies.length; i++) {
    var c = cookies[i];
    while (c.charAt(0) == ' ')
      c = c.substring(1, c.length);

    if (c.indexOf(searchName) == 0)
      return c.substring(searchName.length, c.length);
  }

  return null;
}

var eraseCookie = function (name) {
  writeCookie(name, '', -1);
}


// -------------------------------------
// read write cookie

    var sayHello = function() {
      userName = readCookie('irock_username');
      if (userName)
        alert('Hello ' + userName + ', I missed you.');
      else
        alert('Hello, I am your pet rock.');
    };

    var touchRock = function() {
      if (userName) {
        alert('I like the attention, ' + userName + '. Thank you!');
      } else {
        userName = prompt('What is your name?', '');
        if (userName) {
          alert('It is good to meet you, ' + userName);
          writeCookie('irock_username', userName, 5 * 365);
          console.log(userName);
        }
      }