Question

Using JQuery how to check if any checkboxes are checked and then set the first to checked if none are checked.

var Checked = $('.ProductImageGallery').find(".DfaultCheckbox:selected);

if (Checked == null) { $('.DfaultCheckbox:first').attr('checked', true) }

Answer 1

You can select checked checkboxes with the :checked selector, and then test the .length of the returned jQuery object to see if any elements matched:

if ($(".ProductImageGallery .DfaultCheckbox:checked").length === 0)
   $(".DfaultCheckbox:first").prop("checked", true);

Further reading: http://api.jquery.com/category/selectors/

Note: I’ve used the .prop() method rather than .attr(), but .prop() only works if you’re using jQuery 1.6+ (otherwise stick with .attr()).