single-category-select.php

<script>
(function($){
    $(document).ready(function(){
        $('#divisiondiv .selectit').on('click', function(event){
            var targetElement = event.target;
            if($(targetElement).prop("tagName") == 'INPUT'){
                var elements = $('#divisiondiv .selectit').find('input[type="checkbox"]');
                $(elements).each(function(){
                    if(targetElement != this){
                        $(this).prop("checked", false);
                    }
                });
            }
        });
    });
 })(jQuery);
</script>
<?php 
function er_snell_admin_script($hook) {
    global $post_type;
    if(($hook == "post.php" || $hook == "post-new.php") && $post_type == 'project'){
		wp_enqueue_script( 'project-admin', get_theme_file_uri("assets/js/admin-post.js"), array('jquery'), VERSION, true );
	}
}
add_action( 'admin_enqueue_scripts', 'er_snell_admin_script');