UTM Parser to Web Form

<script>
  function UTMParserFormFill(
    sourceSelector,
    mediumSelector,
    campaignSelector,
    contentSelector,
    termSelector,
    utm_adgroup ){

  // SEARCH PARAMETERS
  // search for any utm parameters within the query string
  // create a cookie from those utm query string key values

  for (var i = sourceSelector.length - 1; i >= 0; i--) {

   // create function that establishes cookie from query string key / channel type values
   function createCookie(utmcookie){
   var now = new Date();
   var time = now.getTime();
   var expireTime = time + 1000*60*15;
   now.setTime(expireTime);
   document.cookie = "utmcookie=" + utmcookie+';expires='+now.toGMTString()+';path=/';
   }

   // getCookie function
   function getCookie(cname) {
      var name = cname + "=";
      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);
        if (c.indexOf(name) == 0) return c.substring(name.length,c.length);
      }
      return "";
    }

  // make sure there aren't any existing cookies
  if( !getCookie("utmcookie").length > 0 ){

  // if url contains any utm parameters run code
  if(window.location.href.indexOf("utm") > -1){

  // slice parameters to return query string
  var QueryString = function () {
    var query_string = {};
    var query = window.location.search.substring(1);
    var vars = query.split("&");
    for (var i=0;i<vars.length;i++) {
      var pair = vars[i].split("=");
      if (typeof query_string[pair[0]] === "undefined") {
        query_string[pair[0]] = pair[1];
      } else if (typeof query_string[pair[0]] === "string") {
        var arr = [ query_string[pair[0]], pair[1] ];
        query_string[pair[0]] = arr;
      } else {
        query_string[pair[0]].push(pair[1]);
      }
    }
    return query_string;
  } ();

  // call each utm query string key value
  // establish identifier of each key value followed by that key value ( separated by "=")
  // separate each utm type by "|"
  var utmcookie = "utm_source=" + QueryString.utm_source + "|" + "utm_medium=" + QueryString.utm_medium + "|" + "utm_campaign=" + QueryString.utm_campaign + "|" + "utm_content=" + QueryString.utm_content + "|" + "utm_term=" + QueryString.utm_term + "|" + "utm_adgroup=" + QueryString.utm_adgroup;

  createCookie(utmcookie);
  }else{
  // if UTM isn't present extract source / medium by
  // Direct
  // Organic
  // Referral

  // list of all prominent Search Engines
  // can be found here http://antezeta.com/news/google-analytics-default-search-engines
  var searchEngines = new RegExp("(about|alice|aol|ask|search\.avg|isearch\.babylon|baidu|bing|searchh\.conduit|google|incredimail}lycos|mamma|msn|naver|search\.netscape|pchome|search-results|terra|yahoo|yam|yandex)\.com|biglobe\.ne\.jp|cnn\.com\/SEARCH\/|search\.comcast\.net|daum\.net|eniro\.se|go\.mail\.ru|goo\.ne\.jp|kvasir\.no|najdi\.org\.mk|online\.onetcenter\.org|ozu\.es|rakuten\.co\.jp|\.rambler\.ru|search\.centrum\.cz|seznam\.cz|startsiden\.no|search\.virgilio\.it|voila\.fr|wp\.pl", "g");

    if( document.referrer.match( searchEngines ) ){
      var utmcookie = "utm_source=" + document.referrer + "|" + "utm_medium=" + "organic" + "|" + "utm_campaign=" + "undefined" + "|" + "utm_content=" + "undefined" + "|" + "utm_term=" + "undefined" + "|" + "utm_adgroup=" + "undefined";

      createCookie(utmcookie);
    }else if( document.referrer.length > 0 && !document.referrer.match(/safestep/g) ){
      var utmcookie = "utm_source=" + document.referrer + "|" + "utm_medium=" + "referral" + "|" + "utm_campaign=" + "undefined" + "|" + "utm_content=" + "undefined" + "|" + "utm_term=" + "undefined" + "|" + "utm_adgroup=" + "undefined";

      createCookie(utmcookie);
    }else{
      var utmcookie = "utm_source=" + "direct" + "|" + "utm_medium=" + "none" + "|" + "utm_campaign=" + "undefined" + "|" + "utm_content=" + "undefined" + "|" + "utm_term=" + "undefined" + "|" + "utm_adgroup=" + "undefined";

      createCookie(utmcookie);
    }
  }
  }

  if( sourceSelector != null || mediumSelector != null ){
  // FORM FILL
  // search for any utm cookies exist
  // add the cookie values into the form

  for (var i = sourceSelector.length - 1; i >= 0; i--) {

  // identify each form element by ID and store in variable
  var utm_source =  sourceSelector[i].value;
  var utm_medium = mediumSelector[i].value;
  var utm_campaign = campaignSelector[i].value;
  var utm_content = contentSelector[i].value;
  var utm_term = termSelector[i].value;
  var utm_adgroup = adgroupSelector[i].value;

  // slice all cookies by cookie name
  if (document.cookie.indexOf("utmcookie") > -1 == true){

    // get utm cookie
    utmcookie = getCookie("utmcookie");

    // if utm cookie exists run code
    if(utmcookie != null == true){

          // individually slice each utm parameter[i] value from
          // the pipe delimiter and establish[i] value into the form per variable

          // if returned "undefined", do nothing

          // utm_source
          if( utm_source != null == true ){
            var source = utmcookie.split('|')[0].split('=').slice(1)
            if( source == "undefined" ){ stop() }else{ sourceSelector[i].value = source; }
          }
          // utm_medium
          if( utm_medium != null == true ){
            var medium = utmcookie.split('|')[1].split('=').slice(1)
            if( medium == "undefined" ){ stop() }else{ mediumSelector[i].value = medium; }
          }
          // utm_campaign
          if( utm_campaign != null == true ){
            var campaign = utmcookie.split('|')[2].split('=').slice(1)
            if( campaign == "undefined" ){ stop() }else{ campaignSelector[i].value = campaign; }
          }
          // utm_content
          if( utm_content != null == true ){
            var content = utmcookie.split('|')[3].split('=').slice(1)
            if( content == "undefined" ){ stop() }else{ contentSelector[i].value = content; }
          }
          // utm_term
          if( utm_term != null == true ){
            var term = utmcookie.split('|')[4].split('=').slice(1)
            if( term == "undefined" ){ stop() }else{ termSelector[i].value = term; }
          }
          // utm_adgroup
          if( utm_adgroup != null == true ){
            var adgroup = utmcookie.split('|')[5].split('=').slice(1)
            if( adgroup == "undefined" ){ stop() }else{ adgroupSelector[i].value = adgroup; }
          }
        }
      }
    }
  }
  }
  }

  var sourceSelector = document.querySelectorAll('[name*="txtutm_source"]');
  var mediumSelector = document.querySelectorAll('[name*="txtutm_medium"]');
  var campaignSelector = document.querySelectorAll('[name*="txtutm_campaign"]');
  var contentSelector = document.querySelectorAll('[name*="txtutm_content"]');
  var termSelector = document.querySelectorAll('[name*="txtutm_term"]');
  var adgroupSelector = document.querySelectorAll('[name*="txtutm_adgroup"]');

  UTMParserFormFill(
    sourceSelector,
    mediumSelector,
    campaignSelector,
    contentSelector,
    termSelector,
    adgroupSelector )

</script>