数据表-jQuery / Javascript下拉框包含空选择器

Question

I have made a dropdown filter for my datatable, as you can see in the jsfiddle ( https://jsfiddle.net/6k0bshb6/45/ ) there is an option which contains no data - if you look through inspect element <option value=""></option> how can I remove this empty container and tell my datatable function for dropdown boxes to skip appending options to the select option when they are empty.

// Dropdown filter function for dataTable from hidden column number 5 for filtering gifts.
       initComplete: function () {
            this.api().columns(5).every(function () {
                var column = this;
                var select = $('<select><option value="">Show all</option></select>')
                    .appendTo($("#contracts_control-panel").find("div").eq(1)) // append dropdown to div 2 in control panel
                    .on('change', function () {
                    var val = $.fn.dataTable.util.escapeRegex(
                    $(this).val());
                    column.search(val ? '^' + val + '$' : '', true, false)
                        .draw();
                        dataTable.page.len(5).draw(); //reset pagination after dropdown filter change.
                });
                column.data().unique().sort().each(function (d, j) {
                    select.append('<option value="' + d + '">' + d + '</option>')
                });
            });
        }
    });

I tried wrapping an if statement around the append like this...

column.data().unique().sort().each(function (d, j) {
      if (d !== undefined) {
                select.append('<option value="' + d + '">' + d + '</option>')
      }
            });

but it didn't work for some reason.

Answer 1

you can modified like this

column.data().unique().sort().each(function (d, j) {
     d&&d.length&&select.append('<option value="' + d + '">' + d + '</option>')
});

I found one row lose its value as below:

Answer 2

Use d !== "" instead of d !== undefined . See fiddle .

column.data().unique().sort().each(function (d, j) {
  if (d !== "") {
            select.append('<option value="' + d + '">' + d + '</option>')
  }
});

Answer 3

You could set the value of "Show All" like below.

<select><option value="Show All">Show all</option><option value=""></option><option value="Free Biscuits">Free Biscuits</option><option value="Free PS4">Free PS4</option><option value="Free TV">Free TV</option><option value="Free XBOX">Free XBOX</option></select>

And once the page load is complete, you could use JQuery to remove the empty drop down option. The below option remove the dropdown item based on index

$('.dropdown-filter-div option:eq(1)').remove()

or use the below JQuery, the below code removes the dropdown item based on value (which is empty in your code)

$('.dropdown-filter-div option[value=""]').remove()

Hope this helps.