Plugins/features/conditionalPageLength/dataTables.conditionalPageLength.js

/**
 * @summary     ConditionalPageLength
 * @description Hide the page length control when the amount of pages is <= 1
 * @version     1.0.0
 * @file        dataTables.conditionalPageLength.js
 * @author      Garrett Hyder (https://github.com/garretthyder)
 * @contact     garrett.m.hyder@gmail.com
 * @copyright   Copyright 2020 Garrett Hyder
 *
 * License      MIT - http://datatables.net/license/mit
 *
 * This feature plugin for DataTables hides the page length control when the amount
 * of pages is <= 1. The control can either appear / disappear or fade in / out.
 *
 * Based off conditionalPaging by Matthew Hasbach (https://github.com/mjhasbach)
 * Reference: https://github.com/DataTables/Plugins/blob/master/features/conditionalPaging/dataTables.conditionalPaging.js
 *
 * @example
 *    $('#myTable').DataTable({
 *        conditionalPageLength: true
 *    });
 *
 * @example
 *    $('#myTable').DataTable({
 *        conditionalPageLength: {
 *            style: 'fade',
 *            speed: 500 // optional
 *        }
 *    });
 *
 * Conditionally hide the Page Length options that are less than the current result size.
 * @example
 *    $('#myTable').DataTable({
 *        conditionalPageLength: {
 *            conditionalOptions: true
 *        }
 *    }); 
 */

(function(window, document, $) {
    $(document).on('init.dt', function(e, dtSettings) {
        if ( e.namespace !== 'dt' ) {
            return;
        }

        var options = dtSettings.oInit.conditionalPageLength || $.fn.dataTable.defaults.conditionalPageLength,
            lengthMenu = dtSettings.aLengthMenu || $.fn.dataTable.defaults.lengthMenu,
            lengthMenuValues = Array.isArray(lengthMenu[0]) ? lengthMenu[0] : lengthMenu;
            
        lengthMenuValues = lengthMenuValues.filter(function(n) { return n > 0 });
        var smallestLength = Math.min.apply(Math, lengthMenuValues);

        if ($.isPlainObject(options) || options === true) {
            var config = $.isPlainObject(options) ? options : {},
                api = new $.fn.dataTable.Api(dtSettings),
                speed = 'slow',
                conditionalPageLength = function(e) {
                    var $paging = $(api.table().container()).find('div.dataTables_length'),
                        pages = api.page.info().pages,
                        size = api.rows({search:'applied'}).count();

                    if (e instanceof $.Event) {
                        if (pages <= 1 && size <= smallestLength) {
                            if (config.style === 'fade') {
                                $paging.stop().fadeTo(speed, 0);
                            }
                            else {
                                $paging.css('visibility', 'hidden');
                            }
                        }
                        else {
                            if (config.style === 'fade') {
                                $paging.stop().fadeTo(speed, 1);
                            }
                            else {
                                $paging.css('visibility', '');
                            }
                        }
                    }
                    else if (pages <= 1 && size <= smallestLength) {
                        if (config.style === 'fade') {
                            $paging.css('opacity', 0);
                        }
                        else {
                            $paging.css('visibility', 'hidden');
                        }
                    }

                    if (config.conditionalOptions) {
                        $paging.find('select option').each(function(index) {
                            if ($(this).attr('value') > size) {
                                $(this).hide();
                            } else {
                                $(this).show();
                            }
                        });
                    }
                };

            if ( config.speed !== undefined ) {
                speed = config.speed;
            }

            conditionalPageLength();

            api.on('draw.dt', conditionalPageLength);
        }
    });
})(window, document, jQuery);