code: function getInnerHtmlFromElement(page, ph, selector, callback) {
      function getInnerHtml(selector) {
          return document.querySelector(selector).innerHTML;
      }
  
      page.evaluate(getInnerHtml, function (result) {
          if (result) {
              callback(null, page, ph, result);
          } else {
              var errorString = 'Error finding innerHTML';
              callback(errorString, page, ph, null);
          }
      }, selector);
  }
docs: Evaluates gets the innerHTML of a certain selected element on a apge
  @param page
  @param ph
  @param selector
  @param {pageResultCallback} callback