Answers

• allan Posts: 63,498Questions: 1Answers: 10,471 Site admin

  June 26 Answer ✓

  I think you are right - a Javascript focus event handler on all elements in the table would be needed for this. Get the position of the currently focused element, see if it is under the fixed header or not, and reposition the scrolling of the page to make it visible.

  It would be quite possible. I'd welcome a pull request from yourself or anyone else who is able to work on this.

  Allan
• pawcza Posts: 5Questions: 1Answers: 0

  June 28

  allan,

  Thanks for the answer. I'll see if I can work on this when I get a chance.

  Wondering if anyone else has some ideas?
• pawcza Posts: 5Questions: 1Answers: 0

  July 1

  I have worked a bit on a solution. The first draft I have is below. This code will scroll user up 100 pixels when the position of the tabbed a tag is within 70 pixels from the top.

  //helper method to determine position of the element relative to view
  function getViewportPosition(element) {
  const rect = element.getBoundingClientRect();

              return {
                  left: rect.left,
                  top: rect.top
              };
          }
  
          //helper method to determine position of the element relative to page
          function getPagePosition(element) {
              const rect = element.getBoundingClientRect();
              return {
                  left: rect.left + window.scrollX,
                  top: rect.top + window.scrollY
              };
          }
  
          //add focus event listener that will make sure rows in datatable are not temporarily obstructed by the fixed header when user tabs backward through links in the table rows 
          document.addEventListener("focus", (e) => {
              //console.log(e.target.nodeName + " (" + e.target.name + ") has focus");
              //console.log(getViewportPosition(e.target).top);
  
              if(e.target.nodeName === 'A' && getViewportPosition(e.target).top < 70){
                  //scroll user up 100 pixels
                  $("html, body").animate({ 
                       scrollTop: getPagePosition(e.target).top - 100 }, 500
                   );
              }
  
          }, true);
  
• allan Posts: 63,498Questions: 1Answers: 10,471 Site admin

  July 2

  Nice one! Thanks for sharing that with us.

  Allan
• pawcza Posts: 5Questions: 1Answers: 0

  July 2

  You bet!
• pawcza Posts: 5Questions: 1Answers: 0

  July 29

  Just wanted to share our final solution. We opted out to do the following:

  • Link the following javascript file to your page:

   //add below code to drawCallbackFunc function where you change display each time the data table is redrawn
      //or to any other code where rows are added/refreshed in data table
      /*
      $(".dataTables_wrapper a").on("focus", function() {
          scrollPageUp(
              element=$(this),
              headerHeight=130
          );
          return false;
      });
      */
  
      //scroll page up if focus is on the element within headerHeight
      function scrollPageUp(element,headerHeight){
          //get position of the element on the screen as seen by the user
          $thisTrueTop = element.offset().top - $(window).scrollTop();        
          //get position of the element on the html page
          $thisDocumentTop = element.offset().top;
          //set how many pixels we will be scrolling up by
          $offsetPixels = headerHeight + 35;
  
          if($thisTrueTop < headerHeight){
              //scroll user up by offsetPixels
              $("html, body").animate({ 
                   scrollTop: $thisDocumentTop  - $offsetPixels  }, 500
               );
          }
      }
  

  • To get the fix to actually work, you need to add the following code to the place where you initialize your data tables, in the drawCallback setting. You can adjust the headerHeight to different number, if your header is larger/smaller, just make sure to test the setting with different browser window sizes and different browsers. headerHeight is in pixels.

  Example:

  $('#myTable').DataTable({
                 "dom": "<'marginrightshow'l><'toolbar'><'alignleft marginrightshow'B><'alignleft marginrightshow'f><'clearboth'>t<'clearboth'><'clearboth'><'bottom'i><'alignleft marginrightshow'p><'pageBar'>", 
                 "fixedHeader": {
                                                                             header: true,
                                                                             footer: false
                                                              },
  ...
  drawCallback: function(settings) {
                 drawCallbackFunc(settings);
                 },
  ...
  
  

  And then add this code after the data table initialization:

  // each time the table is redrawn
  function drawCallbackFunc(settings) {       
             $(".dataTables_wrapper a").on("focus", function() {
                              scrollPageUp(
                                  element=$(this),
                                  headerHeight=130
                              );
                              return false;
             });
  }
  

  • If your datatable is dynamic with code that adds/updates rows, you’ll also need to add the listener to your code after the row is added/updated.
• allan Posts: 63,498Questions: 1Answers: 10,471 Site admin

  July 29

  Awesome - thank you for the follow up!

  Allan