code: function getElementsByClassName(elem, name, tag) {
          if (elem.getElementsByClassName) {
              return elem.getElementsByClassName(name);
          }
  
          var elements = [];
          var elems = elem.getElementsByTagName(tag || '*');
          name = ' ' + name + ' ';
  
          each(elems, function (elem) {
              if ((' ' + (elem.className || '') + ' ').indexOf(name) >= 0) {
                  elements.push(elem);
              }
          });
  
          return elements;
      }
docs: Get elements By className for IE8-
  
  @param {Element} elem element
  @param {String} name className
  @param {String} tag tagName
  
  @returns {HTMLCollection|Array}