getUrlParameter.js

//decode uri
var getUrlParameter = function getUrlParameter(sParam) {
  var sPageURL = decodeURIComponent(window.location.search.substring(1)),
    sURLVariables = sPageURL.split("&"),
    sParameterName,
    i;
  for (i = 0; i < sURLVariables.length; i++) {
    sParameterName = sURLVariables[i].split("=");
    if (sParameterName[0] === sParam) {
      return sParameterName[1] === undefined
        ? ""
        : sParameterName[1].replace("/", "");
    }
  }
  return "";
};
var track = getUrlParameter("track");
var subid = getUrlParameter("subid");
var znak = getUrlParameter("znak_name");
var znakText = document.querySelectorAll(".znak");
for (var i = 0; i < znakText.length; i++) {
  znakText[i].innerText = znak;
}