Removes all query parameters from the url beginning with 'utm_', leaves anchors (#) and other query params alone

gtm-utm-remover.js

/**
 * GTM utm_ remover
 * License: MIT
 * Author: @CanRau
 * Version: 0.2.0
 * 
 * Removes all query parameters from the url beginning with 'utm_'
 * Leaves anchors (#) and other query params alone, so
 * example.com/?session=SESSIONID&utm_source=instagram#content
 * would become
 * example.com/?session=SESSIONID#content
 *
 * Works only in Browsers supporting the History API
 * https://caniuse.com/#feat=history
 * 
 * Usage:
 * 1. Store this script in a Google Tag Manager variable
 * 2. Open the tag you want this to get fired (I use Google Universal Analytics - Pageview - All pages)
 * 3. Enable override settings
 * 4. Define a field called 'hitCallback'
 * 5. Set the value to the in 1. created variable using the lego brick icon
 * 6. Save & publish
 *
 * Changelog:
 * 0.2.0: improves regex
 */

function() {
  return function() {
    if (!!(window.history && history.pushState)) {
      if (/(\?|&)utm_.*=/.test(window.location.search)) {
        window.history.replaceState({}, document.title, document.location.pathname + document.location.search.substring(1).split('&').filter(function(x) {return !/^utm_.*=/.test(x)}).join('&').replace(/^(.*)/, '?$1') + document.location.hash)
      }
      if (/\?$/.test(document.location.href)) {
        window.history.replaceState({}, document.title, document.location.pathname)
      }
    }
  }
}