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

  function selectAffiliateField() {
    // IMPORTANT: The form field ID where you want to store the cookie value
    var fieldId = "affiliate_id_f1687";
    return document.getElementById(fieldId);
  }

  var affiliateFieldPresent = selectAffiliateField();

  if (affiliateFieldPresent) {
    getCookie("affwp_ref", function(id) {
      selectAffiliateField().value = id;
    });
    getCookie("affwp_erl_id", function(id) {
      selectAffiliateField().value = id;
    });
  }