utils.js

//set event on documnet but fire if target is true
document.addEventListener('click', function(e) {
    var clsList = Array.prototype.slice.call(e.target.classList);
    if(cls.indexOf('hero-heading') > -1) {
         console.log('hello');
    }
})

function cssAnimationEvent(element, type, callback) {
  var self = this;
  var pfx = ["webkit", "moz", "MS", "o", ""];
  for (var p = 0; p < pfx.length; p++) {
    if (!pfx[p]) type = type.toLowerCase();
      element.addEventListener(pfx[p]+type, function() { 
        callback(element); 
    }, false);
  }
}


//image prelaoder with promise. Note you need a polyfill for promise to work.
function preloadImage(src) {
  var promise = new Promise(function(resolve, reject){
      var image = new Image();
      image.src = src;
      image.onload = function() {
          resolve();
      }
      image.onerror = function() {
          reject(Error('Image'+ src +' faled to load'));
      }
  });
  return promise;
}

//simple jsonp function
function jsonp(url, callback) {
  var callbackName = 'jsonp_callback_' + Math.round(100000 * Math.random());
  window[callbackName] = function(data) {
      delete window[callbackName];
      document.body.removeChild(script);
      callback(data);
  };
  var script = document.createElement('script');
  script.src = url + (url.indexOf('?') >= 0 ? '&' : '?') + 'callback=' + callbackName;
  document.body.appendChild(script);
}


getUrlParameter = function getUrlParameter(sParam) {
    var sPageURL = window.location.search.substring(1);
    var sURLVariables = sPageURL.split('&');
    var sParameterName = void 0;
    var i = void 0;

    for (i = 0; i < sURLVariables.length; i++) {
        sParameterName = sURLVariables[i].split('=');

        if (sParameterName[0] === sParam) {
            return sParameterName[1] === undefined ? true : decodeURIComponent(sParameterName[1]);
        }
    }
    return '';
};