comparison core/misc/tabledrag.es6.js @ 0:4c8ae668cc8c

Initial import (non-working)

+/**
+ * @file
+ * Provide dragging capabilities to admin uis.
+ */
+
+/**
+ * Triggers when weights columns are toggled.
+ *
+ * @event columnschange
+ */
+
+(function ($, Drupal, drupalSettings) {
+  /**
+   * Store the state of weight columns display for all tables.
+   *
+   * Default value is to hide weight columns.
+   */
+  let showWeight = JSON.parse(localStorage.getItem('Drupal.tableDrag.showWeight'));
+
+  /**
+   * Drag and drop table rows with field manipulation.
+   *
+   * Using the drupal_attach_tabledrag() function, any table with weights or
+   * parent relationships may be made into draggable tables. Columns containing
+   * a field may optionally be hidden, providing a better user experience.
+   *
+   * Created tableDrag instances may be modified with custom behaviors by
+   * overriding the .onDrag, .onDrop, .row.onSwap, and .row.onIndent methods.
+   * See blocks.js for an example of adding additional functionality to
+   * tableDrag.
+   *
+   * @type {Drupal~behavior}
+   */
+  Drupal.behaviors.tableDrag = {
+    attach(context, settings) {
+      function initTableDrag(table, base) {
+        if (table.length) {
+          // Create the new tableDrag instance. Save in the Drupal variable
+          // to allow other scripts access to the object.
+          Drupal.tableDrag[base] = new Drupal.tableDrag(table[0], settings.tableDrag[base]);
+        }
+      }
+
+      for (const base in settings.tableDrag) {
+        if (settings.tableDrag.hasOwnProperty(base)) {
+          initTableDrag($(context).find(`#${base}`).once('tabledrag'), base);
+        }
+      }
+    },
+  };
+
+  /**
+   * Provides table and field manipulation.
+   *
+   * @constructor
+   *
+   * @param {HTMLElement} table
+   *   DOM object for the table to be made draggable.
+   * @param {object} tableSettings
+   *   Settings for the table added via drupal_add_dragtable().
+   */
+  Drupal.tableDrag = function (table, tableSettings) {
+    const self = this;
+    const $table = $(table);
+
+    /**
+     * @type {jQuery}
+     */
+    this.$table = $(table);
+
+    /**
+     *
+     * @type {HTMLElement}
+     */
+    this.table = table;
+
+    /**
+     * @type {object}
+     */
+    this.tableSettings = tableSettings;
+
+    /**
+     * Used to hold information about a current drag operation.
+     *
+     * @type {?HTMLElement}
+     */
+    this.dragObject = null;
+
+    /**
+     * Provides operations for row manipulation.
+     *
+     * @type {?HTMLElement}
+     */
+    this.rowObject = null;
+
+    /**
+     * Remember the previous element.
+     *
+     * @type {?HTMLElement}
+     */
+    this.oldRowElement = null;
+
+    /**
+     * Used to determine up or down direction from last mouse move.
+     *
+     * @type {number}
+     */
+    this.oldY = 0;
+
+    /**
+     * Whether anything in the entire table has changed.
+     *
+     * @type {bool}
+     */
+    this.changed = false;
+
+    /**
+     * Maximum amount of allowed parenting.
+     *
+     * @type {number}
+     */
+    this.maxDepth = 0;
+
+    /**
+     * Direction of the table.
+     *
+     * @type {number}
+     */
+    this.rtl = $(this.table).css('direction') === 'rtl' ? -1 : 1;
+
+    /**
+     *
+     * @type {bool}
+     */
+    this.striping = $(this.table).data('striping') === 1;
+
+    /**
+     * Configure the scroll settings.
+     *
+     * @type {object}
+     *
+     * @prop {number} amount
+     * @prop {number} interval
+     * @prop {number} trigger
+     */
+    this.scrollSettings = { amount: 4, interval: 50, trigger: 70 };
+
+    /**
+     *
+     * @type {?number}
+     */
+    this.scrollInterval = null;
+
+    /**
+     *
+     * @type {number}
+     */
+    this.scrollY = 0;
+
+    /**
+     *
+     * @type {number}
+     */
+    this.windowHeight = 0;
+
+    /**
+     * Check this table's settings for parent relationships.
+     *
+     * For efficiency, large sections of code can be skipped if we don't need to
+     * track horizontal movement and indentations.
+     *
+     * @type {bool}
+     */
+    this.indentEnabled = false;
+    for (const group in tableSettings) {
+      if (tableSettings.hasOwnProperty(group)) {
+        for (const n in tableSettings[group]) {
+          if (tableSettings[group].hasOwnProperty(n)) {
+            if (tableSettings[group][n].relationship === 'parent') {
+              this.indentEnabled = true;
+            }
+            if (tableSettings[group][n].limit > 0) {
+              this.maxDepth = tableSettings[group][n].limit;
+            }
+          }
+        }
+      }
+    }
+    if (this.indentEnabled) {
+      /**
+       * Total width of indents, set in makeDraggable.
+       *
+       * @type {number}
+       */
+      this.indentCount = 1;
+      // Find the width of indentations to measure mouse movements against.
+      // Because the table doesn't need to start with any indentations, we
+      // manually append 2 indentations in the first draggable row, measure
+      // the offset, then remove.
+      const indent = Drupal.theme('tableDragIndentation');
+      const testRow = $('<tr/>').addClass('draggable').appendTo(table);
+      const testCell = $('<td/>').appendTo(testRow).prepend(indent).prepend(indent);
+      const $indentation = testCell.find('.js-indentation');
+
+      /**
+       *
+       * @type {number}
+       */
+      this.indentAmount = $indentation.get(1).offsetLeft - $indentation.get(0).offsetLeft;
+      testRow.remove();
+    }
+
+    // Make each applicable row draggable.
+    // Match immediate children of the parent element to allow nesting.
+    $table.find('> tr.draggable, > tbody > tr.draggable').each(function () {
+      self.makeDraggable(this);
+    });
+
+    // Add a link before the table for users to show or hide weight columns.
+    $table.before($('<button type="button" class="link tabledrag-toggle-weight"></button>')
+      .attr('title', Drupal.t('Re-order rows by numerical weight instead of dragging.'))
+      .on('click', $.proxy(function (e) {
+        e.preventDefault();
+        this.toggleColumns();
+      }, this))
+      .wrap('<div class="tabledrag-toggle-weight-wrapper"></div>')
+      .parent(),
+    );
+
+    // Initialize the specified columns (for example, weight or parent columns)
+    // to show or hide according to user preference. This aids accessibility
+    // so that, e.g., screen reader users can choose to enter weight values and
+    // manipulate form elements directly, rather than using drag-and-drop..
+    self.initColumns();
+
+    // Add event bindings to the document. The self variable is passed along
+    // as event handlers do not have direct access to the tableDrag object.
+    $(document).on('touchmove', event => self.dragRow(event.originalEvent.touches[0], self));
+    $(document).on('touchend', event => self.dropRow(event.originalEvent.touches[0], self));
+    $(document).on('mousemove pointermove', event => self.dragRow(event, self));
+    $(document).on('mouseup pointerup', event => self.dropRow(event, self));
+
+    // React to localStorage event showing or hiding weight columns.
+    $(window).on('storage', $.proxy(function (e) {
+      // Only react to 'Drupal.tableDrag.showWeight' value change.
+      if (e.originalEvent.key === 'Drupal.tableDrag.showWeight') {
+        // This was changed in another window, get the new value for this
+        // window.
+        showWeight = JSON.parse(e.originalEvent.newValue);
+        this.displayColumns(showWeight);
+      }
+    }, this));
+  };
+
+  /**
+   * Initialize columns containing form elements to be hidden by default.
+   *
+   * Identify and mark each cell with a CSS class so we can easily toggle
+   * show/hide it. Finally, hide columns if user does not have a
+   * 'Drupal.tableDrag.showWeight' localStorage value.
+   */
+  Drupal.tableDrag.prototype.initColumns = function () {
+    const $table = this.$table;
+    let hidden;
+    let cell;
+    let columnIndex;
+    for (const group in this.tableSettings) {
+      if (this.tableSettings.hasOwnProperty(group)) {
+        // Find the first field in this group.
+        for (const d in this.tableSettings[group]) {
+          if (this.tableSettings[group].hasOwnProperty(d)) {
+            const field = $table.find(`.${this.tableSettings[group][d].target}`).eq(0);
+            if (field.length && this.tableSettings[group][d].hidden) {
+              hidden = this.tableSettings[group][d].hidden;
+              cell = field.closest('td');
+              break;
+            }
+          }
+        }
+
+        // Mark the column containing this field so it can be hidden.
+        if (hidden && cell[0]) {
+          // Add 1 to our indexes. The nth-child selector is 1 based, not 0
+          // based. Match immediate children of the parent element to allow
+          // nesting.
+          columnIndex = cell.parent().find('> td').index(cell.get(0)) + 1;
+          $table.find('> thead > tr, > tbody > tr, > tr').each(this.addColspanClass(columnIndex));
+        }
+      }
+    }
+    this.displayColumns(showWeight);
+  };
+
+  /**
+   * Mark cells that have colspan.
+   *
+   * In order to adjust the colspan instead of hiding them altogether.
+   *
+   * @param {number} columnIndex
+   *   The column index to add colspan class to.
+   *
+   * @return {function}
+   *   Function to add colspan class.
+   */
+  Drupal.tableDrag.prototype.addColspanClass = function (columnIndex) {
+    return function () {
+      // Get the columnIndex and adjust for any colspans in this row.
+      const $row = $(this);
+      let index = columnIndex;
+      const cells = $row.children();
+      let cell;
+      cells.each(function (n) {
+        if (n < index && this.colSpan && this.colSpan > 1) {
+          index -= this.colSpan - 1;
+        }
+      });
+      if (index > 0) {
+        cell = cells.filter(`:nth-child(${index})`);
+        if (cell[0].colSpan && cell[0].colSpan > 1) {
+          // If this cell has a colspan, mark it so we can reduce the colspan.
+          cell.addClass('tabledrag-has-colspan');
+        }
+        else {
+          // Mark this cell so we can hide it.
+          cell.addClass('tabledrag-hide');
+        }
+      }
+    };
+  };
+
+  /**
+   * Hide or display weight columns. Triggers an event on change.
+   *
+   * @fires event:columnschange
+   *
+   * @param {bool} displayWeight
+   *   'true' will show weight columns.
+   */
+  Drupal.tableDrag.prototype.displayColumns = function (displayWeight) {
+    if (displayWeight) {
+      this.showColumns();
+    }
+    // Default action is to hide columns.
+    else {
+      this.hideColumns();
+    }
+    // Trigger an event to allow other scripts to react to this display change.
+    // Force the extra parameter as a bool.
+    $('table').findOnce('tabledrag').trigger('columnschange', !!displayWeight);
+  };
+
+  /**
+   * Toggle the weight column depending on 'showWeight' value.
+   *
+   * Store only default override.
+   */
+  Drupal.tableDrag.prototype.toggleColumns = function () {
+    showWeight = !showWeight;
+    this.displayColumns(showWeight);
+    if (showWeight) {
+      // Save default override.
+      localStorage.setItem('Drupal.tableDrag.showWeight', showWeight);
+    }
+    else {
+      // Reset the value to its default.
+      localStorage.removeItem('Drupal.tableDrag.showWeight');
+    }
+  };
+
+  /**
+   * Hide the columns containing weight/parent form elements.
+   *
+   * Undo showColumns().
+   */
+  Drupal.tableDrag.prototype.hideColumns = function () {
+    const $tables = $('table').findOnce('tabledrag');
+    // Hide weight/parent cells and headers.
+    $tables.find('.tabledrag-hide').css('display', 'none');
+    // Show TableDrag handles.
+    $tables.find('.tabledrag-handle').css('display', '');
+    // Reduce the colspan of any effected multi-span columns.
+    $tables.find('.tabledrag-has-colspan').each(function () {
+      this.colSpan = this.colSpan - 1;
+    });
+    // Change link text.
+    $('.tabledrag-toggle-weight').text(Drupal.t('Show row weights'));
+  };
+
+  /**
+   * Show the columns containing weight/parent form elements.
+   *
+   * Undo hideColumns().
+   */
+  Drupal.tableDrag.prototype.showColumns = function () {
+    const $tables = $('table').findOnce('tabledrag');
+    // Show weight/parent cells and headers.
+    $tables.find('.tabledrag-hide').css('display', '');
+    // Hide TableDrag handles.
+    $tables.find('.tabledrag-handle').css('display', 'none');
+    // Increase the colspan for any columns where it was previously reduced.
+    $tables.find('.tabledrag-has-colspan').each(function () {
+      this.colSpan = this.colSpan + 1;
+    });
+    // Change link text.
+    $('.tabledrag-toggle-weight').text(Drupal.t('Hide row weights'));
+  };
+
+  /**
+   * Find the target used within a particular row and group.
+   *
+   * @param {string} group
+   *   Group selector.
+   * @param {HTMLElement} row
+   *   The row HTML element.
+   *
+   * @return {object}
+   *   The table row settings.
+   */
+  Drupal.tableDrag.prototype.rowSettings = function (group, row) {
+    const field = $(row).find(`.${group}`);
+    const tableSettingsGroup = this.tableSettings[group];
+    for (const delta in tableSettingsGroup) {
+      if (tableSettingsGroup.hasOwnProperty(delta)) {
+        const targetClass = tableSettingsGroup[delta].target;
+        if (field.is(`.${targetClass}`)) {
+          // Return a copy of the row settings.
+          const rowSettings = {};
+          for (const n in tableSettingsGroup[delta]) {
+            if (tableSettingsGroup[delta].hasOwnProperty(n)) {
+              rowSettings[n] = tableSettingsGroup[delta][n];
+            }
+          }
+          return rowSettings;
+        }
+      }
+    }
+  };
+
+  /**
+   * Take an item and add event handlers to make it become draggable.
+   *
+   * @param {HTMLElement} item
+   *   The item to add event handlers to.
+   */
+  Drupal.tableDrag.prototype.makeDraggable = function (item) {
+    const self = this;
+    const $item = $(item);
+    // Add a class to the title link.
+    $item.find('td:first-of-type').find('a').addClass('menu-item__link');
+    // Create the handle.
+    const handle = $('<a href="#" class="tabledrag-handle"><div class="handle">&nbsp;</div></a>').attr('title', Drupal.t('Drag to re-order'));
+    // Insert the handle after indentations (if any).
+    const $indentationLast = $item.find('td:first-of-type').find('.js-indentation').eq(-1);
+    if ($indentationLast.length) {
+      $indentationLast.after(handle);
+      // Update the total width of indentation in this entire table.
+      self.indentCount = Math.max($item.find('.js-indentation').length, self.indentCount);
+    }
+    else {
+      $item.find('td').eq(0).prepend(handle);
+    }
+
+    handle.on('mousedown touchstart pointerdown', (event) => {
+      event.preventDefault();
+      if (event.originalEvent.type === 'touchstart') {
+        event = event.originalEvent.touches[0];
+      }
+      self.dragStart(event, self, item);
+    });
+
+    // Prevent the anchor tag from jumping us to the top of the page.
+    handle.on('click', (e) => {
+      e.preventDefault();
+    });
+
+    // Set blur cleanup when a handle is focused.
+    handle.on('focus', () => {
+      self.safeBlur = true;
+    });
+
+    // On blur, fire the same function as a touchend/mouseup. This is used to
+    // update values after a row has been moved through the keyboard support.
+    handle.on('blur', (event) => {
+      if (self.rowObject && self.safeBlur) {
+        self.dropRow(event, self);
+      }
+    });
+
+    // Add arrow-key support to the handle.
+    handle.on('keydown', (event) => {
+      // If a rowObject doesn't yet exist and this isn't the tab key.
+      if (event.keyCode !== 9 && !self.rowObject) {
+        self.rowObject = new self.row(item, 'keyboard', self.indentEnabled, self.maxDepth, true);
+      }
+
+      let keyChange = false;
+      let groupHeight;
+
+      /* eslint-disable no-fallthrough */
+
+      switch (event.keyCode) {
+        // Left arrow.
+        case 37:
+        // Safari left arrow.
+        case 63234:
+          keyChange = true;
+          self.rowObject.indent(-1 * self.rtl);
+          break;
+
+        // Up arrow.
+        case 38:
+        // Safari up arrow.
+        case 63232:
+          var $previousRow = $(self.rowObject.element).prev('tr:first-of-type');
+          var previousRow = $previousRow.get(0);
+          while (previousRow && $previousRow.is(':hidden')) {
+            $previousRow = $(previousRow).prev('tr:first-of-type');
+            previousRow = $previousRow.get(0);
+          }
+          if (previousRow) {
+            // Do not allow the onBlur cleanup.
+            self.safeBlur = false;
+            self.rowObject.direction = 'up';
+            keyChange = true;
+
+            if ($(item).is('.tabledrag-root')) {
+              // Swap with the previous top-level row.
+              groupHeight = 0;
+              while (previousRow && $previousRow.find('.js-indentation').length) {
+                $previousRow = $(previousRow).prev('tr:first-of-type');
+                previousRow = $previousRow.get(0);
+                groupHeight += $previousRow.is(':hidden') ? 0 : previousRow.offsetHeight;
+              }
+              if (previousRow) {
+                self.rowObject.swap('before', previousRow);
+                // No need to check for indentation, 0 is the only valid one.
+                window.scrollBy(0, -groupHeight);
+              }
+            }
+            else if (self.table.tBodies[0].rows[0] !== previousRow || $previousRow.is('.draggable')) {
+              // Swap with the previous row (unless previous row is the first
+              // one and undraggable).
+              self.rowObject.swap('before', previousRow);
+              self.rowObject.interval = null;
+              self.rowObject.indent(0);
+              window.scrollBy(0, -parseInt(item.offsetHeight, 10));
+            }
+            // Regain focus after the DOM manipulation.
+            handle.trigger('focus');
+          }
+          break;
+
+        // Right arrow.
+        case 39:
+        // Safari right arrow.
+        case 63235:
+          keyChange = true;
+          self.rowObject.indent(self.rtl);
+          break;
+
+        // Down arrow.
+        case 40:
+        // Safari down arrow.
+        case 63233:
+          var $nextRow = $(self.rowObject.group).eq(-1).next('tr:first-of-type');
+          var nextRow = $nextRow.get(0);
+          while (nextRow && $nextRow.is(':hidden')) {
+            $nextRow = $(nextRow).next('tr:first-of-type');
+            nextRow = $nextRow.get(0);
+          }
+          if (nextRow) {
+            // Do not allow the onBlur cleanup.
+            self.safeBlur = false;
+            self.rowObject.direction = 'down';
+            keyChange = true;
+
+            if ($(item).is('.tabledrag-root')) {
+              // Swap with the next group (necessarily a top-level one).
+              groupHeight = 0;
+              const nextGroup = new self.row(nextRow, 'keyboard', self.indentEnabled, self.maxDepth, false);
+              if (nextGroup) {
+                $(nextGroup.group).each(function () {
+                  groupHeight += $(this).is(':hidden') ? 0 : this.offsetHeight;
+                });
+                const nextGroupRow = $(nextGroup.group).eq(-1).get(0);
+                self.rowObject.swap('after', nextGroupRow);
+                // No need to check for indentation, 0 is the only valid one.
+                window.scrollBy(0, parseInt(groupHeight, 10));
+              }
+            }
+            else {
+              // Swap with the next row.
+              self.rowObject.swap('after', nextRow);
+              self.rowObject.interval = null;
+              self.rowObject.indent(0);
+              window.scrollBy(0, parseInt(item.offsetHeight, 10));
+            }
+            // Regain focus after the DOM manipulation.
+            handle.trigger('focus');
+          }
+          break;
+      }
+
+      /* eslint-enable no-fallthrough */
+
+      if (self.rowObject && self.rowObject.changed === true) {
+        $(item).addClass('drag');
+        if (self.oldRowElement) {
+          $(self.oldRowElement).removeClass('drag-previous');
+        }
+        self.oldRowElement = item;
+        if (self.striping === true) {
+          self.restripeTable();
+        }
+        self.onDrag();
+      }
+
+      // Returning false if we have an arrow key to prevent scrolling.
+      if (keyChange) {
+        return false;
+      }
+    });
+
+    // Compatibility addition, return false on keypress to prevent unwanted
+    // scrolling. IE and Safari will suppress scrolling on keydown, but all
+    // other browsers need to return false on keypress.
+    // http://www.quirksmode.org/js/keys.html
+    handle.on('keypress', (event) => {
+      /* eslint-disable no-fallthrough */
+
+      switch (event.keyCode) {
+        // Left arrow.
+        case 37:
+        // Up arrow.
+        case 38:
+        // Right arrow.
+        case 39:
+        // Down arrow.
+        case 40:
+          return false;
+      }
+
+      /* eslint-enable no-fallthrough */
+    });
+  };
+
+  /**
+   * Pointer event initiator, creates drag object and information.
+   *
+   * @param {jQuery.Event} event
+   *   The event object that trigger the drag.
+   * @param {Drupal.tableDrag} self
+   *   The drag handle.
+   * @param {HTMLElement} item
+   *   The item that that is being dragged.
+   */
+  Drupal.tableDrag.prototype.dragStart = function (event, self, item) {
+    // Create a new dragObject recording the pointer information.
+    self.dragObject = {};
+    self.dragObject.initOffset = self.getPointerOffset(item, event);
+    self.dragObject.initPointerCoords = self.pointerCoords(event);
+    if (self.indentEnabled) {
+      self.dragObject.indentPointerPos = self.dragObject.initPointerCoords;
+    }
+
+    // If there's a lingering row object from the keyboard, remove its focus.
+    if (self.rowObject) {
+      $(self.rowObject.element).find('a.tabledrag-handle').trigger('blur');
+    }
+
+    // Create a new rowObject for manipulation of this row.
+    self.rowObject = new self.row(item, 'pointer', self.indentEnabled, self.maxDepth, true);
+
+    // Save the position of the table.
+    self.table.topY = $(self.table).offset().top;
+    self.table.bottomY = self.table.topY + self.table.offsetHeight;
+
+    // Add classes to the handle and row.
+    $(item).addClass('drag');
+
+    // Set the document to use the move cursor during drag.
+    $('body').addClass('drag');
+    if (self.oldRowElement) {
+      $(self.oldRowElement).removeClass('drag-previous');
+    }
+  };
+
+  /**
+   * Pointer movement handler, bound to document.
+   *
+   * @param {jQuery.Event} event
+   *   The pointer event.
+   * @param {Drupal.tableDrag} self
+   *   The tableDrag instance.
+   *
+   * @return {bool|undefined}
+   *   Undefined if no dragObject is defined, false otherwise.
+   */
+  Drupal.tableDrag.prototype.dragRow = function (event, self) {
+    if (self.dragObject) {
+      self.currentPointerCoords = self.pointerCoords(event);
+      const y = self.currentPointerCoords.y - self.dragObject.initOffset.y;
+      const x = self.currentPointerCoords.x - self.dragObject.initOffset.x;
+
+      // Check for row swapping and vertical scrolling.
+      if (y !== self.oldY) {
+        self.rowObject.direction = y > self.oldY ? 'down' : 'up';
+        // Update the old value.
+        self.oldY = y;
+        // Check if the window should be scrolled (and how fast).
+        const scrollAmount = self.checkScroll(self.currentPointerCoords.y);
+        // Stop any current scrolling.
+        clearInterval(self.scrollInterval);
+        // Continue scrolling if the mouse has moved in the scroll direction.
+        if (scrollAmount > 0 && self.rowObject.direction === 'down' || scrollAmount < 0 && self.rowObject.direction === 'up') {
+          self.setScroll(scrollAmount);
+        }
+
+        // If we have a valid target, perform the swap and restripe the table.
+        const currentRow = self.findDropTargetRow(x, y);
+        if (currentRow) {
+          if (self.rowObject.direction === 'down') {
+            self.rowObject.swap('after', currentRow, self);
+          }
+          else {
+            self.rowObject.swap('before', currentRow, self);
+          }
+          if (self.striping === true) {
+            self.restripeTable();
+          }
+        }
+      }
+
+      // Similar to row swapping, handle indentations.
+      if (self.indentEnabled) {
+        const xDiff = self.currentPointerCoords.x - self.dragObject.indentPointerPos.x;
+        // Set the number of indentations the pointer has been moved left or
+        // right.
+        const indentDiff = Math.round(xDiff / self.indentAmount);
+        // Indent the row with our estimated diff, which may be further
+        // restricted according to the rows around this row.
+        const indentChange = self.rowObject.indent(indentDiff);
+        // Update table and pointer indentations.
+        self.dragObject.indentPointerPos.x += self.indentAmount * indentChange * self.rtl;
+        self.indentCount = Math.max(self.indentCount, self.rowObject.indents);
+      }
+
+      return false;
+    }
+  };
+
+  /**
+   * Pointerup behavior.
+   *
+   * @param {jQuery.Event} event
+   *   The pointer event.
+   * @param {Drupal.tableDrag} self
+   *   The tableDrag instance.
+   */
+  Drupal.tableDrag.prototype.dropRow = function (event, self) {
+    let droppedRow;
+    let $droppedRow;
+
+    // Drop row functionality.
+    if (self.rowObject !== null) {
+      droppedRow = self.rowObject.element;
+      $droppedRow = $(droppedRow);
+      // The row is already in the right place so we just release it.
+      if (self.rowObject.changed === true) {
+        // Update the fields in the dropped row.
+        self.updateFields(droppedRow);
+
+        // If a setting exists for affecting the entire group, update all the
+        // fields in the entire dragged group.
+        for (const group in self.tableSettings) {
+          if (self.tableSettings.hasOwnProperty(group)) {
+            const rowSettings = self.rowSettings(group, droppedRow);
+            if (rowSettings.relationship === 'group') {
+              for (const n in self.rowObject.children) {
+                if (self.rowObject.children.hasOwnProperty(n)) {
+                  self.updateField(self.rowObject.children[n], group);
+                }
+              }
+            }
+          }
+        }
+
+        self.rowObject.markChanged();
+        if (self.changed === false) {
+          $(Drupal.theme('tableDragChangedWarning')).insertBefore(self.table).hide().fadeIn('slow');
+          self.changed = true;
+        }
+      }
+
+      if (self.indentEnabled) {
+        self.rowObject.removeIndentClasses();
+      }
+      if (self.oldRowElement) {
+        $(self.oldRowElement).removeClass('drag-previous');
+      }
+      $droppedRow.removeClass('drag').addClass('drag-previous');
+      self.oldRowElement = droppedRow;
+      self.onDrop();
+      self.rowObject = null;
+    }
+
+    // Functionality specific only to pointerup events.
+    if (self.dragObject !== null) {
+      self.dragObject = null;
+      $('body').removeClass('drag');
+      clearInterval(self.scrollInterval);
+    }
+  };
+
+  /**
+   * Get the coordinates from the event (allowing for browser differences).
+   *
+   * @param {jQuery.Event} event
+   *   The pointer event.
+   *
+   * @return {object}
+   *   An object with `x` and `y` keys indicating the position.
+   */
+  Drupal.tableDrag.prototype.pointerCoords = function (event) {
+    if (event.pageX || event.pageY) {
+      return { x: event.pageX, y: event.pageY };
+    }
+    return {
+      x: event.clientX + document.body.scrollLeft - document.body.clientLeft,
+      y: event.clientY + document.body.scrollTop - document.body.clientTop,
+    };
+  };
+
+  /**
+   * Get the event offset from the target element.
+   *
+   * Given a target element and a pointer event, get the event offset from that
+   * element. To do this we need the element's position and the target position.
+   *
+   * @param {HTMLElement} target
+   *   The target HTML element.
+   * @param {jQuery.Event} event
+   *   The pointer event.
+   *
+   * @return {object}
+   *   An object with `x` and `y` keys indicating the position.
+   */
+  Drupal.tableDrag.prototype.getPointerOffset = function (target, event) {
+    const docPos = $(target).offset();
+    const pointerPos = this.pointerCoords(event);
+    return { x: pointerPos.x - docPos.left, y: pointerPos.y - docPos.top };
+  };
+
+  /**
+   * Find the row the mouse is currently over.
+   *
+   * This row is then taken and swapped with the one being dragged.
+   *
+   * @param {number} x
+   *   The x coordinate of the mouse on the page (not the screen).
+   * @param {number} y
+   *   The y coordinate of the mouse on the page (not the screen).
+   *
+   * @return {*}
+   *   The drop target row, if found.
+   */
+  Drupal.tableDrag.prototype.findDropTargetRow = function (x, y) {
+    const rows = $(this.table.tBodies[0].rows).not(':hidden');
+    for (let n = 0; n < rows.length; n++) {
+      let row = rows[n];
+      let $row = $(row);
+      const rowY = $row.offset().top;
+      var rowHeight;
+      // Because Safari does not report offsetHeight on table rows, but does on
+      // table cells, grab the firstChild of the row and use that instead.
+      // http://jacob.peargrove.com/blog/2006/technical/table-row-offsettop-bug-in-safari.
+      if (row.offsetHeight === 0) {
+        rowHeight = parseInt(row.firstChild.offsetHeight, 10) / 2;
+      }
+      // Other browsers.
+      else {
+        rowHeight = parseInt(row.offsetHeight, 10) / 2;
+      }
+
+      // Because we always insert before, we need to offset the height a bit.
+      if ((y > (rowY - rowHeight)) && (y < (rowY + rowHeight))) {
+        if (this.indentEnabled) {
+          // Check that this row is not a child of the row being dragged.
+          for (n in this.rowObject.group) {
+            if (this.rowObject.group[n] === row) {
+              return null;
+            }
+          }
+        }
+        else {
+          // Do not allow a row to be swapped with itself.
+          if (row === this.rowObject.element) {
+            return null;
+          }
+        }
+
+        // Check that swapping with this row is allowed.
+        if (!this.rowObject.isValidSwap(row)) {
+          return null;
+        }
+
+        // We may have found the row the mouse just passed over, but it doesn't
+        // take into account hidden rows. Skip backwards until we find a
+        // draggable row.
+        while ($row.is(':hidden') && $row.prev('tr').is(':hidden')) {
+          $row = $row.prev('tr:first-of-type');
+          row = $row.get(0);
+        }
+        return row;
+      }
+    }
+    return null;
+  };
+
+  /**
+   * After the row is dropped, update the table fields.
+   *
+   * @param {HTMLElement} changedRow
+   *   DOM object for the row that was just dropped.
+   */
+  Drupal.tableDrag.prototype.updateFields = function (changedRow) {
+    for (const group in this.tableSettings) {
+      if (this.tableSettings.hasOwnProperty(group)) {
+        // Each group may have a different setting for relationship, so we find
+        // the source rows for each separately.
+        this.updateField(changedRow, group);
+      }
+    }
+  };
+
+  /**
+   * After the row is dropped, update a single table field.
+   *
+   * @param {HTMLElement} changedRow
+   *   DOM object for the row that was just dropped.
+   * @param {string} group
+   *   The settings group on which field updates will occur.
+   */
+  Drupal.tableDrag.prototype.updateField = function (changedRow, group) {
+    let rowSettings = this.rowSettings(group, changedRow);
+    const $changedRow = $(changedRow);
+    let sourceRow;
+    let $previousRow;
+    let previousRow;
+    let useSibling;
+    // Set the row as its own target.
+    if (rowSettings.relationship === 'self' || rowSettings.relationship === 'group') {
+      sourceRow = changedRow;
+    }
+    // Siblings are easy, check previous and next rows.
+    else if (rowSettings.relationship === 'sibling') {
+      $previousRow = $changedRow.prev('tr:first-of-type');
+      previousRow = $previousRow.get(0);
+      const $nextRow = $changedRow.next('tr:first-of-type');
+      const nextRow = $nextRow.get(0);
+      sourceRow = changedRow;
+      if ($previousRow.is('.draggable') && $previousRow.find(`.${group}`).length) {
+        if (this.indentEnabled) {
+          if ($previousRow.find('.js-indentations').length === $changedRow.find('.js-indentations').length) {
+            sourceRow = previousRow;
+          }
+        }
+        else {
+          sourceRow = previousRow;
+        }
+      }
+      else if ($nextRow.is('.draggable') && $nextRow.find(`.${group}`).length) {
+        if (this.indentEnabled) {
+          if ($nextRow.find('.js-indentations').length === $changedRow.find('.js-indentations').length) {
+            sourceRow = nextRow;
+          }
+        }
+        else {
+          sourceRow = nextRow;
+        }
+      }
+    }
+    // Parents, look up the tree until we find a field not in this group.
+    // Go up as many parents as indentations in the changed row.
+    else if (rowSettings.relationship === 'parent') {
+      $previousRow = $changedRow.prev('tr');
+      previousRow = $previousRow;
+      while ($previousRow.length && $previousRow.find('.js-indentation').length >= this.rowObject.indents) {
+        $previousRow = $previousRow.prev('tr');
+        previousRow = $previousRow;
+      }
+      // If we found a row.
+      if ($previousRow.length) {
+        sourceRow = $previousRow.get(0);
+      }
+      // Otherwise we went all the way to the left of the table without finding
+      // a parent, meaning this item has been placed at the root level.
+      else {
+        // Use the first row in the table as source, because it's guaranteed to
+        // be at the root level. Find the first item, then compare this row
+        // against it as a sibling.
+        sourceRow = $(this.table).find('tr.draggable:first-of-type').get(0);
+        if (sourceRow === this.rowObject.element) {
+          sourceRow = $(this.rowObject.group[this.rowObject.group.length - 1]).next('tr.draggable').get(0);
+        }
+        useSibling = true;
+      }
+    }
+
+    // Because we may have moved the row from one category to another,
+    // take a look at our sibling and borrow its sources and targets.
+    this.copyDragClasses(sourceRow, changedRow, group);
+    rowSettings = this.rowSettings(group, changedRow);
+
+    // In the case that we're looking for a parent, but the row is at the top
+    // of the tree, copy our sibling's values.
+    if (useSibling) {
+      rowSettings.relationship = 'sibling';
+      rowSettings.source = rowSettings.target;
+    }
+
+    const targetClass = `.${rowSettings.target}`;
+    const targetElement = $changedRow.find(targetClass).get(0);
+
+    // Check if a target element exists in this row.
+    if (targetElement) {
+      const sourceClass = `.${rowSettings.source}`;
+      const sourceElement = $(sourceClass, sourceRow).get(0);
+      switch (rowSettings.action) {
+        case 'depth':
+          // Get the depth of the target row.
+          targetElement.value = $(sourceElement).closest('tr').find('.js-indentation').length;
+          break;
+
+        case 'match':
+          // Update the value.
+          targetElement.value = sourceElement.value;
+          break;
+
+        case 'order':
+          var siblings = this.rowObject.findSiblings(rowSettings);
+          if ($(targetElement).is('select')) {
+            // Get a list of acceptable values.
+            const values = [];
+            $(targetElement).find('option').each(function () {
+              values.push(this.value);
+            });
+            const maxVal = values[values.length - 1];
+            // Populate the values in the siblings.
+            $(siblings).find(targetClass).each(function () {
+              // If there are more items than possible values, assign the
+              // maximum value to the row.
+              if (values.length > 0) {
+                this.value = values.shift();
+              }
+              else {
+                this.value = maxVal;
+              }
+            });
+          }
+          else {
+            // Assume a numeric input field.
+            let weight = parseInt($(siblings[0]).find(targetClass).val(), 10) || 0;
+            $(siblings).find(targetClass).each(function () {
+              this.value = weight;
+              weight++;
+            });
+          }
+          break;
+      }
+    }
+  };
+
+  /**
+   * Copy all tableDrag related classes from one row to another.
+   *
+   * Copy all special tableDrag classes from one row's form elements to a
+   * different one, removing any special classes that the destination row
+   * may have had.
+   *
+   * @param {HTMLElement} sourceRow
+   *   The element for the source row.
+   * @param {HTMLElement} targetRow
+   *   The element for the target row.
+   * @param {string} group
+   *   The group selector.
+   */
+  Drupal.tableDrag.prototype.copyDragClasses = function (sourceRow, targetRow, group) {
+    const sourceElement = $(sourceRow).find(`.${group}`);
+    const targetElement = $(targetRow).find(`.${group}`);
+    if (sourceElement.length && targetElement.length) {
+      targetElement[0].className = sourceElement[0].className;
+    }
+  };
+
+  /**
+   * Check the suggested scroll of the table.
+   *
+   * @param {number} cursorY
+   *   The Y position of the cursor.
+   *
+   * @return {number}
+   *   The suggested scroll.
+   */
+  Drupal.tableDrag.prototype.checkScroll = function (cursorY) {
+    const de = document.documentElement;
+    const b = document.body;
+
+    const windowHeight = this.windowHeight = window.innerHeight || (de.clientHeight && de.clientWidth !== 0 ? de.clientHeight : b.offsetHeight);
+    let scrollY;
+    if (document.all) {
+      scrollY = this.scrollY = !de.scrollTop ? b.scrollTop : de.scrollTop;
+    }
+    else {
+      scrollY = this.scrollY = window.pageYOffset ? window.pageYOffset : window.scrollY;
+    }
+    const trigger = this.scrollSettings.trigger;
+    let delta = 0;
+
+    // Return a scroll speed relative to the edge of the screen.
+    if (cursorY - scrollY > windowHeight - trigger) {
+      delta = trigger / (windowHeight + scrollY - cursorY);
+      delta = (delta > 0 && delta < trigger) ? delta : trigger;
+      return delta * this.scrollSettings.amount;
+    }
+    else if (cursorY - scrollY < trigger) {
+      delta = trigger / (cursorY - scrollY);
+      delta = (delta > 0 && delta < trigger) ? delta : trigger;
+      return -delta * this.scrollSettings.amount;
+    }
+  };
+
+  /**
+   * Set the scroll for the table.
+   *
+   * @param {number} scrollAmount
+   *   The amount of scroll to apply to the window.
+   */
+  Drupal.tableDrag.prototype.setScroll = function (scrollAmount) {
+    const self = this;
+
+    this.scrollInterval = setInterval(() => {
+      // Update the scroll values stored in the object.
+      self.checkScroll(self.currentPointerCoords.y);
+      const aboveTable = self.scrollY > self.table.topY;
+      const belowTable = self.scrollY + self.windowHeight < self.table.bottomY;
+      if (scrollAmount > 0 && belowTable || scrollAmount < 0 && aboveTable) {
+        window.scrollBy(0, scrollAmount);
+      }
+    }, this.scrollSettings.interval);
+  };
+
+  /**
+   * Command to restripe table properly.
+   */
+  Drupal.tableDrag.prototype.restripeTable = function () {
+    // :even and :odd are reversed because jQuery counts from 0 and
+    // we count from 1, so we're out of sync.
+    // Match immediate children of the parent element to allow nesting.
+    $(this.table).find('> tbody > tr.draggable, > tr.draggable')
+      .filter(':visible')
+      .filter(':odd').removeClass('odd').addClass('even').end()
+      .filter(':even').removeClass('even').addClass('odd');
+  };
+
+  /**
+   * Stub function. Allows a custom handler when a row begins dragging.
+   *
+   * @return {null}
+   *   Returns null when the stub function is used.
+   */
+  Drupal.tableDrag.prototype.onDrag = function () {
+    return null;
+  };
+
+  /**
+   * Stub function. Allows a custom handler when a row is dropped.
+   *
+   * @return {null}
+   *   Returns null when the stub function is used.
+   */
+  Drupal.tableDrag.prototype.onDrop = function () {
+    return null;
+  };
+
+  /**
+   * Constructor to make a new object to manipulate a table row.
+   *
+   * @param {HTMLElement} tableRow
+   *   The DOM element for the table row we will be manipulating.
+   * @param {string} method
+   *   The method in which this row is being moved. Either 'keyboard' or
+   *   'mouse'.
+   * @param {bool} indentEnabled
+   *   Whether the containing table uses indentations. Used for optimizations.
+   * @param {number} maxDepth
+   *   The maximum amount of indentations this row may contain.
+   * @param {bool} addClasses
+   *   Whether we want to add classes to this row to indicate child
+   *   relationships.
+   */
+  Drupal.tableDrag.prototype.row = function (tableRow, method, indentEnabled, maxDepth, addClasses) {
+    const $tableRow = $(tableRow);
+
+    this.element = tableRow;
+    this.method = method;
+    this.group = [tableRow];
+    this.groupDepth = $tableRow.find('.js-indentation').length;
+    this.changed = false;
+    this.table = $tableRow.closest('table')[0];
+    this.indentEnabled = indentEnabled;
+    this.maxDepth = maxDepth;
+    // Direction the row is being moved.
+    this.direction = '';
+    if (this.indentEnabled) {
+      this.indents = $tableRow.find('.js-indentation').length;
+      this.children = this.findChildren(addClasses);
+      this.group = $.merge(this.group, this.children);
+      // Find the depth of this entire group.
+      for (let n = 0; n < this.group.length; n++) {
+        this.groupDepth = Math.max($(this.group[n]).find('.js-indentation').length, this.groupDepth);
+      }
+    }
+  };
+
+  /**
+   * Find all children of rowObject by indentation.
+   *
+   * @param {bool} addClasses
+   *   Whether we want to add classes to this row to indicate child
+   *   relationships.
+   *
+   * @return {Array}
+   *   An array of children of the row.
+   */
+  Drupal.tableDrag.prototype.row.prototype.findChildren = function (addClasses) {
+    const parentIndentation = this.indents;
+    let currentRow = $(this.element, this.table).next('tr.draggable');
+    const rows = [];
+    let child = 0;
+
+    function rowIndentation(indentNum, el) {
+      const self = $(el);
+      if (child === 1 && (indentNum === parentIndentation)) {
+        self.addClass('tree-child-first');
+      }
+      if (indentNum === parentIndentation) {
+        self.addClass('tree-child');
+      }
+      else if (indentNum > parentIndentation) {
+        self.addClass('tree-child-horizontal');
+      }
+    }
+
+    while (currentRow.length) {
+      // A greater indentation indicates this is a child.
+      if (currentRow.find('.js-indentation').length > parentIndentation) {
+        child++;
+        rows.push(currentRow[0]);
+        if (addClasses) {
+          currentRow.find('.js-indentation').each(rowIndentation);
+        }
+      }
+      else {
+        break;
+      }
+      currentRow = currentRow.next('tr.draggable');
+    }
+    if (addClasses && rows.length) {
+      $(rows[rows.length - 1]).find(`.js-indentation:nth-child(${parentIndentation + 1})`).addClass('tree-child-last');
+    }
+    return rows;
+  };
+
+  /**
+   * Ensure that two rows are allowed to be swapped.
+   *
+   * @param {HTMLElement} row
+   *   DOM object for the row being considered for swapping.
+   *
+   * @return {bool}
+   *   Whether the swap is a valid swap or not.
+   */
+  Drupal.tableDrag.prototype.row.prototype.isValidSwap = function (row) {
+    const $row = $(row);
+    if (this.indentEnabled) {
+      let prevRow;
+      let nextRow;
+      if (this.direction === 'down') {
+        prevRow = row;
+        nextRow = $row.next('tr').get(0);
+      }
+      else {
+        prevRow = $row.prev('tr').get(0);
+        nextRow = row;
+      }
+      this.interval = this.validIndentInterval(prevRow, nextRow);
+
+      // We have an invalid swap if the valid indentations interval is empty.
+      if (this.interval.min > this.interval.max) {
+        return false;
+      }
+    }
+
+    // Do not let an un-draggable first row have anything put before it.
+    if (this.table.tBodies[0].rows[0] === row && $row.is(':not(.draggable)')) {
+      return false;
+    }
+
+    return true;
+  };
+
+  /**
+   * Perform the swap between two rows.
+   *
+   * @param {string} position
+   *   Whether the swap will occur 'before' or 'after' the given row.
+   * @param {HTMLElement} row
+   *   DOM element what will be swapped with the row group.
+   */
+  Drupal.tableDrag.prototype.row.prototype.swap = function (position, row) {
+    // Makes sure only DOM object are passed to Drupal.detachBehaviors().
+    this.group.forEach((row) => {
+      Drupal.detachBehaviors(row, drupalSettings, 'move');
+    });
+    $(row)[position](this.group);
+    // Makes sure only DOM object are passed to Drupal.attachBehaviors()s.
+    this.group.forEach((row) => {
+      Drupal.attachBehaviors(row, drupalSettings);
+    });
+    this.changed = true;
+    this.onSwap(row);
+  };
+
+  /**
+   * Determine the valid indentations interval for the row at a given position.
+   *
+   * @param {?HTMLElement} prevRow
+   *   DOM object for the row before the tested position
+   *   (or null for first position in the table).
+   * @param {?HTMLElement} nextRow
+   *   DOM object for the row after the tested position
+   *   (or null for last position in the table).
+   *
+   * @return {object}
+   *   An object with the keys `min` and `max` to indicate the valid indent
+   *   interval.
+   */
+  Drupal.tableDrag.prototype.row.prototype.validIndentInterval = function (prevRow, nextRow) {
+    const $prevRow = $(prevRow);
+    let minIndent;
+    let maxIndent;
+
+    // Minimum indentation:
+    // Do not orphan the next row.
+    minIndent = nextRow ? $(nextRow).find('.js-indentation').length : 0;
+
+    // Maximum indentation:
+    if (!prevRow || $prevRow.is(':not(.draggable)') || $(this.element).is('.tabledrag-root')) {
+      // Do not indent:
+      // - the first row in the table,
+      // - rows dragged below a non-draggable row,
+      // - 'root' rows.
+      maxIndent = 0;
+    }
+    else {
+      // Do not go deeper than as a child of the previous row.
+      maxIndent = $prevRow.find('.js-indentation').length + ($prevRow.is('.tabledrag-leaf') ? 0 : 1);
+      // Limit by the maximum allowed depth for the table.
+      if (this.maxDepth) {
+        maxIndent = Math.min(maxIndent, this.maxDepth - (this.groupDepth - this.indents));
+      }
+    }
+
+    return { min: minIndent, max: maxIndent };
+  };
+
+  /**
+   * Indent a row within the legal bounds of the table.
+   *
+   * @param {number} indentDiff
+   *   The number of additional indentations proposed for the row (can be
+   *   positive or negative). This number will be adjusted to nearest valid
+   *   indentation level for the row.
+   *
+   * @return {number}
+   *   The number of indentations applied.
+   */
+  Drupal.tableDrag.prototype.row.prototype.indent = function (indentDiff) {
+    const $group = $(this.group);
+    // Determine the valid indentations interval if not available yet.
+    if (!this.interval) {
+      const prevRow = $(this.element).prev('tr').get(0);
+      const nextRow = $group.eq(-1).next('tr').get(0);
+      this.interval = this.validIndentInterval(prevRow, nextRow);
+    }
+
+    // Adjust to the nearest valid indentation.
+    let indent = this.indents + indentDiff;
+    indent = Math.max(indent, this.interval.min);
+    indent = Math.min(indent, this.interval.max);
+    indentDiff = indent - this.indents;
+
+    for (let n = 1; n <= Math.abs(indentDiff); n++) {
+      // Add or remove indentations.
+      if (indentDiff < 0) {
+        $group.find('.js-indentation:first-of-type').remove();
+        this.indents--;
+      }
+      else {
+        $group.find('td:first-of-type').prepend(Drupal.theme('tableDragIndentation'));
+        this.indents++;
+      }
+    }
+    if (indentDiff) {
+      // Update indentation for this row.
+      this.changed = true;
+      this.groupDepth += indentDiff;
+      this.onIndent();
+    }
+
+    return indentDiff;
+  };
+
+  /**
+   * Find all siblings for a row.
+   *
+   * According to its subgroup or indentation. Note that the passed-in row is
+   * included in the list of siblings.
+   *
+   * @param {object} rowSettings
+   *   The field settings we're using to identify what constitutes a sibling.
+   *
+   * @return {Array}
+   *   An array of siblings.
+   */
+  Drupal.tableDrag.prototype.row.prototype.findSiblings = function (rowSettings) {
+    const siblings = [];
+    const directions = ['prev', 'next'];
+    const rowIndentation = this.indents;
+    let checkRowIndentation;
+    for (let d = 0; d < directions.length; d++) {
+      let checkRow = $(this.element)[directions[d]]();
+      while (checkRow.length) {
+        // Check that the sibling contains a similar target field.
+        if (checkRow.find(`.${rowSettings.target}`)) {
+          // Either add immediately if this is a flat table, or check to ensure
+          // that this row has the same level of indentation.
+          if (this.indentEnabled) {
+            checkRowIndentation = checkRow.find('.js-indentation').length;
+          }
+
+          if (!(this.indentEnabled) || (checkRowIndentation === rowIndentation)) {
+            siblings.push(checkRow[0]);
+          }
+          else if (checkRowIndentation < rowIndentation) {
+            // No need to keep looking for siblings when we get to a parent.
+            break;
+          }
+        }
+        else {
+          break;
+        }
+        checkRow = checkRow[directions[d]]();
+      }
+      // Since siblings are added in reverse order for previous, reverse the
+      // completed list of previous siblings. Add the current row and continue.
+      if (directions[d] === 'prev') {
+        siblings.reverse();
+        siblings.push(this.element);
+      }
+    }
+    return siblings;
+  };
+
+  /**
+   * Remove indentation helper classes from the current row group.
+   */
+  Drupal.tableDrag.prototype.row.prototype.removeIndentClasses = function () {
+    for (const n in this.children) {
+      if (this.children.hasOwnProperty(n)) {
+        $(this.children[n]).find('.js-indentation')
+          .removeClass('tree-child')
+          .removeClass('tree-child-first')
+          .removeClass('tree-child-last')
+          .removeClass('tree-child-horizontal');
+      }
+    }
+  };
+
+  /**
+   * Add an asterisk or other marker to the changed row.
+   */
+  Drupal.tableDrag.prototype.row.prototype.markChanged = function () {
+    const marker = Drupal.theme('tableDragChangedMarker');
+    const cell = $(this.element).find('td:first-of-type');
+    if (cell.find('abbr.tabledrag-changed').length === 0) {
+      cell.append(marker);
+    }
+  };
+
+  /**
+   * Stub function. Allows a custom handler when a row is indented.
+   *
+   * @return {null}
+   *   Returns null when the stub function is used.
+   */
+  Drupal.tableDrag.prototype.row.prototype.onIndent = function () {
+    return null;
+  };
+
+  /**
+   * Stub function. Allows a custom handler when a row is swapped.
+   *
+   * @param {HTMLElement} swappedRow
+   *   The element for the swapped row.
+   *
+   * @return {null}
+   *   Returns null when the stub function is used.
+   */
+  Drupal.tableDrag.prototype.row.prototype.onSwap = function (swappedRow) {
+    return null;
+  };
+
+  $.extend(Drupal.theme, /** @lends Drupal.theme */{
+
+    /**
+     * @return {string}
+     *  Markup for the marker.
+     */
+    tableDragChangedMarker() {
+      return `<abbr class="warning tabledrag-changed" title="${Drupal.t('Changed')}">*</abbr>`;
+    },
+
+    /**
+     * @return {string}
+     *   Markup for the indentation.
+     */
+    tableDragIndentation() {
+      return '<div class="js-indentation indentation">&nbsp;</div>';
+    },
+
+    /**
+     * @return {string}
+     *   Markup for the warning.
+     */
+    tableDragChangedWarning() {
+      return `<div class="tabledrag-changed-warning messages messages--warning" role="alert">${Drupal.theme('tableDragChangedMarker')} ${Drupal.t('You have unsaved changes.')}</div>`;
+    },
+  });
+}(jQuery, Drupal, drupalSettings));