Source: misc/tableresponsive.js

/**
 * @file
 * Responsive table functionality.
 */

(function ($, Drupal, window) {

  'use strict';

  /**
   * Attach the tableResponsive function to {@link Drupal.behaviors}.
   *
   * @type {Drupal~behavior}
   *
   * @prop {Drupal~behaviorAttach} attach
   *   Attaches tableResponsive functionality.
   */
  Drupal.behaviors.tableResponsive = {
    attach: function (context, settings) {
      var $tables = $(context).find('table.responsive-enabled').once('tableresponsive');
      if ($tables.length) {
        var il = $tables.length;
        for (var i = 0; i < il; i++) {
          TableResponsive.tables.push(new TableResponsive($tables[i]));
        }
      }
    }
  };

  /**
   * The TableResponsive object optimizes table presentation for screen size.
   *
   * A responsive table hides columns at small screen sizes, leaving the most
   * important columns visible to the end user. Users should not be prevented
   * from accessing all columns, however. This class adds a toggle to a table
   * with hidden columns that exposes the columns. Exposing the columns will
   * likely break layouts, but it provides the user with a means to access
   * data, which is a guiding principle of responsive design.
   *
   * @constructor Drupal.TableResponsive
   *
   * @param {HTMLElement} table
   *   The table element to initialize the responsive table on.
   */
  function TableResponsive(table) {
    this.table = table;
    this.$table = $(table);
    this.showText = Drupal.t('Show all columns');
    this.hideText = Drupal.t('Hide lower priority columns');
    // Store a reference to the header elements of the table so that the DOM is
    // traversed only once to find them.
    this.$headers = this.$table.find('th');
    // Add a link before the table for users to show or hide weight columns.
    this.$link = $('<button type="button" class="link tableresponsive-toggle"></button>')
      .attr('title', Drupal.t('Show table cells that were hidden to make the table fit within a small screen.'))
      .on('click', $.proxy(this, 'eventhandlerToggleColumns'));

    this.$table.before($('<div class="tableresponsive-toggle-columns"></div>').append(this.$link));

    // Attach a resize handler to the window.
    $(window)
      .on('resize.tableresponsive', $.proxy(this, 'eventhandlerEvaluateColumnVisibility'))
      .trigger('resize.tableresponsive');
  }

  /**
   * Extend the TableResponsive function with a list of managed tables.
   */
  $.extend(TableResponsive, /** @lends Drupal.TableResponsive */{

    /**
     * Store all created instances.
     *
     * @type {Array.<Drupal.TableResponsive>}
     */
    tables: []
  });

  /**
   * Associates an action link with the table that will show hidden columns.
   *
   * Columns are assumed to be hidden if their header has the class priority-low
   * or priority-medium.
   */
  $.extend(TableResponsive.prototype, /** @lends Drupal.TableResponsive# */{

    /**
     * @param {jQuery.Event} e
     *   The event triggered.
     */
    eventhandlerEvaluateColumnVisibility: function (e) {
      var pegged = parseInt(this.$link.data('pegged'), 10);
      var hiddenLength = this.$headers.filter('.priority-medium:hidden, .priority-low:hidden').length;
      // If the table has hidden columns, associate an action link with the
      // table to show the columns.
      if (hiddenLength > 0) {
        this.$link.show().text(this.showText);
      }
      // When the toggle is pegged, its presence is maintained because the user
      // has interacted with it. This is necessary to keep the link visible if
      // the user adjusts screen size and changes the visibility of columns.
      if (!pegged && hiddenLength === 0) {
        this.$link.hide().text(this.hideText);
      }
    },

    /**
     * Toggle the visibility of columns based on their priority.
     *
     * Columns are classed with either 'priority-low' or 'priority-medium'.
     *
     * @param {jQuery.Event} e
     *   The event triggered.
     */
    eventhandlerToggleColumns: function (e) {
      e.preventDefault();
      var self = this;
      var $hiddenHeaders = this.$headers.filter('.priority-medium:hidden, .priority-low:hidden');
      this.$revealedCells = this.$revealedCells || $();
      // Reveal hidden columns.
      if ($hiddenHeaders.length > 0) {
        $hiddenHeaders.each(function (index, element) {
          var $header = $(this);
          var position = $header.prevAll('th').length;
          self.$table.find('tbody tr').each(function () {
            var $cells = $(this).find('td').eq(position);
            $cells.show();
            // Keep track of the revealed cells, so they can be hidden later.
            self.$revealedCells = $().add(self.$revealedCells).add($cells);
          });
          $header.show();
          // Keep track of the revealed headers, so they can be hidden later.
          self.$revealedCells = $().add(self.$revealedCells).add($header);
        });
        this.$link.text(this.hideText).data('pegged', 1);
      }
      // Hide revealed columns.
      else {
        this.$revealedCells.hide();
        // Strip the 'display:none' declaration from the style attributes of
        // the table cells that .hide() added.
        this.$revealedCells.each(function (index, element) {
          var $cell = $(this);
          var properties = $cell.attr('style').split(';');
          var newProps = [];
          // The hide method adds display none to the element. The element
          // should be returned to the same state it was in before the columns
          // were revealed, so it is necessary to remove the display none value
          // from the style attribute.
          var match = /^display\s*\:\s*none$/;
          for (var i = 0; i < properties.length; i++) {
            var prop = properties[i];
            prop.trim();
            // Find the display:none property and remove it.
            var isDisplayNone = match.exec(prop);
            if (isDisplayNone) {
              continue;
            }
            newProps.push(prop);
          }
          // Return the rest of the style attribute values to the element.
          $cell.attr('style', newProps.join(';'));
        });
        this.$link.text(this.showText).data('pegged', 0);
        // Refresh the toggle link.
        $(window).trigger('resize.tableresponsive');
      }
    }
  });

  // Make the TableResponsive object available in the Drupal namespace.
  Drupal.TableResponsive = TableResponsive;

})(jQuery, Drupal, window);