Cookie setzen. Ohne Zeit in Sekunden wird es ein Session Cookie. Ohne Angabe eines Values wird als Wert eine 1 verwendet.

function setCookie(name, seconds = null, value = null) {
  var now = new Date();
  now.setTime(now.getTime() + (seconds * 1000));
  var expires = '';
  if (seconds != null) {
    expires = now.toGMTString();
  }
  var content = 1;
  if (value != null) {
    content = value;
  }
  document.cookie = name + "=" + content + "; expires=" + expires + ";path=/";
}

 Cookie auslesen

function getCookie(name) {
  var nameEQ = name + "=";
  var ca = document.cookie.split(';');
  for (var i = 0; i < ca.length; i++) {
    var c = ca[i];
    while (c.charAt(0) == ' ') c = c.substring(1, c.length);
    if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length, c.length);
  }
  return null;
}

 Cookie löschen

function eraseCookie(name) {
  document.cookie = name + '=; Path=/; Expires=Thu, 01 Jan 1970 00:00:01 GMT;';
}