code: function findElementsContainingText(query, content) {
  
              var results = []; // array to hold results
  
              // workout which property to use to get inner text
              var txtProp = ('textContent' in document) ? 'textContent' : 'innerText';
  
              // get the list of elements to inspect
              var elements = document.querySelectorAll(query);
  
              for (var i = 0, l = elements.length; i < l; i++) {
                  if (elements[i][txtProp].trim() === content.trim()) {
                      results.push(elements[i]);
                  }
              }
  
              return results;
          }
docs: method to execute within the DOM to find elements containing text