ember-sortable

Sortable UI primitives for Ember.

Check out the demo

Requirements

Installation

$ ember install ember-sortable

Usage

{{! app/components/my-list/template.hbs }}

<ol {{sortable-group onChange=this.reorderItems}}>
  {{#each this.items as |item|}}
    <li {{sortable-item model=item}}>
      {{item}}
      <span class='handle' {{sortable-handle}}>&varr;</span>
    </li>
  {{/each}}
</ol>

<p>The last dragged item was: {{this.lastDragged}}</p>

The onChange action is called with two arguments:

• Your item models in their new order
• The model you just dragged

// app/components/my-list/component.js

export default class MyList extends Component {
  @tracked lastDragged;
  @tracked items = ['Coal Ila', 'Askaig', 'Bowmore'];

  @action
  reorderItems(itemModels, draggedModel) {
    this.items = itemModels;
    this.lastDragged = draggedModel;
  }
}

The modifier version does not support groupModel, use the currying of action or the fn helper.

{{! app/components/my-list/template.hbs }}

<ol {{sortable-group onChange=(fn this.reorderItems model)}}>
  {{#each this.items as |item|}}
    <li {{sortable-item model=item}}>
      {{item}}
      <span class='handle' {{sortable-handle}}>&varr;</span>
    </li>
  {{/each}}
</ol>

Changing sort direction

To change sort direction, define direction on sortable-group (default is y):

<ol {{sortable-group direction="x" onChange=(action "reorderItems")}>

Changing spacing between currently dragged element and the rest of the group

When user starts to drag element, other elements jump back. Works both for the x and y direction option.

In y case: elements above current one jump up, and elements below current one - jump down. In x case: elements before current one jump to the left, and elements after current one - jump to the right.

To change this property, define spacing on sortable-item (default is 0):

<li {{sortable-item spacing=15}}>

Changing the drag tolerance

distance attribute changes the tolerance, in pixels, for when sorting should start. If specified, sorting will not start until after mouse is dragged beyond distance. Can be used to allow for clicks on elements within a handle.

<li {{sortable-item distance=30}}>

Disabling reordering

The disabled attribute allows you to disable sorting for the entire group and its child items.

<li {{sortable-group disabled=true}}>

CSS, Animation

Sortable items can be in one of four states: default, dragging, dropping, and activated. The classes look like this:

<!-- Default -->
<li class="sortable-item">...</li>
<!-- Dragging -->
<li class="sortable-item is-dragging">...</li>
<!-- Dropping -->
<li class="sortable-item is-dropping">...</li>
<!-- Keyboard -->
<li class="sortable-item is-activated">...</li>

In our example app.css we apply a transition of .125s in the default case:

.sortable-item {
  transition: all 0.125s;
}

While an item is dragging we want it to move pixel-for-pixel with the user’s mouse so we bring the transition duration to 0. We also give it a highlight color and bring it to the top of the stack:

.sortable-item.is-dragging {
  transition-duration: 0s;
  background: red;
  z-index: 10;
}

While dropping, the is-dragging class is removed and the item returns to its default transition duration. If we wanted to apply a different duration we could do so with the is-dropping class. In our example we opt to simply maintain the z-index and apply a slightly different colour:

.sortable-item.is-dropping {
  background: #f66;
  z-index: 10;
}

If the user presses space to activate and move an item via the keyboard, is-activated is added. Once the user drops the item it is removed. Use this class to add a visual indicator that the item is selected and being manipulated.

Drag Actions

The onDragStart and onDragStop actions are available for the sortable-items. You can provide an action name to listen to these actions to be notified when an item is being dragged or not.

When the action is called, the item's model will be provided as the only argument.

// app/components/my-list/component.js

export default class MyRoute extends Route {
  @action
  dragStarted(item) {
    console.log(`Item started dragging: ${item}`);
  },
  @action
  dragStopped(item) {
    console.log(`Item stopped dragging: ${item}`);
  }
}

<li {{sortable-item onDragStart=this.dragStarted onDragStop=this.dragStopped model=item}}>
  {{item}}
  <span class='handle' {{sortable-handle}}>&varr;</span>
</li>

Multiple Ember-Sortables renders simultaneously

There is a service behind the scenes for communication between the group and the items and to maintain state. It does this seemlessly when the elements are rendered on the screen. However, if there are two sortables rendered at the same time, either in the same component or different components, the state management does not know which items belong to which group.

Both the {{sortable-group}} and {{sortable-item}} take an additional argument groupName. Should you encounter this conflict, assign a groupName to the group and items. You only need to do this for one of the sortables in conflict, but you can on both if you wish.

<ol {{sortable-group groupName='products' onChange=this.reorderItems}}>
  {{#each this.items as |item|}}
    <li {{sortable-item groupName='products' model=item}}>
      {{item}}
      <span class='handle' {{sortable-handle}}>&varr;</span>
    </li>
  {{/each}}
</ol>

Ensure that the same name is passed to both the group and the items, this would be best accomplished by creating property on the component and referring to that property. If you are able to use the {{#let}} helper (useful in template only components), using {{#let}} makes the usage clearer.

{{#let 'products' as |myGroupName|}}
  <ol {{sortable-group groupName=myGroupName onChange=this.reorderItems}}>
    {{#each this.items as |item|}}
      <li {{sortable-item groupName=myGroupName model=item}}>
        {{item}}
        <span class='handle' {{sortable-handle}}>&varr;</span>
      </li>
    {{/each}}
  </ol>
{{/let}}

Disabling Drag (Experimental)

sortable-item exposes an optional disabled (previously isDraggingDisabled) flag that you can use to disable reordering for that particular item. Disabling and item won't prevent it from changing position in the array. The user can still move other non-disabled items to over it.

This flag is intended as an utility to make your life easier with 3 main benefits:

1. You can now specify which sortable-item are not intended to be draggable/sortable.
2. You do not have to duplicate the sortable-item UI just for the purpose of disabling the sorting behavior.
3. Allows you to access the entire list of models for your onChange action, which can now be a mix of sortable and non-sortable items.

Data down, actions up

No data is mutated by sortable-group or sortable-item. In the spirit of “data down, actions up”, a fresh array containing the models from each item in their new order is sent via the group’s onChange action.

Each item takes a model property. This should be fairly self-explanatory but it’s important to note that it doesn’t do anything with this object besides keeping a reference for later use in onChange.

Accessibility

The sortable-group has support for the following accessibility functionality:

Built-in Functionalities

Keyboard Navigation

There are 4 modes during keyboard navigation:

• ACTIVATE enables the keyboard navigation. Activate via ENTER/SPACE
• MOVE enables item(s) to be moved up, down, left, or right based on direction. Activate via ARROW UP/DOWN/LEFT/RIGHT
• CONFIRM submits the new sort order, invokes the onChange action. Activate via ENTER/SPACE.
• CANCEL cancels the new sort order, reverts back to the old sort order. Activate via ESCAPE or when focus is lost.

Focus Management

• When focus is on a item or handle, user can effectively select the item via ENTER/SPACE. This is the ACTIVATE mode.
• While ACTIVATE, the focus is locked on sortable-group container and will not be lost until CONFIRM, CANCEL, or focus is lost.

User configurable

Screen Reader

The default language for ember-sortable is English. Any language can be supported by passing in the configuration below in the appropriate language.

• a11yItemName a name for the item. Defaults to item.
• a11yAnnouncementConfig a map of action enums to functions that takes the following config, which is exposed by sortable-group.

a11yAnnounceConfig = {
  a11yItemName, // name associated with the name
  index, // 0-based
  maxLength, // length of the items
  direction, // x or y
  delta, // +1 means down or right, -1 means up or left
};

and returns a string constructed from the config.

Default value

{
  ACTIVATE: function({ a11yItemName, index, maxLength, direction }) {
    let message = `${a11yItemName} at position, ${index + 1} of ${maxLength}, is activated to be repositioned.`;
    if (direction === 'y') {
      message += 'Press up and down keys to change position,';
    } else {
      message += 'Press left and right keys to change position,';
    }

    message += ' Space to confirm new position, Escape to cancel.';

    return message;
  },
  MOVE: function({ a11yItemName, index, maxLength, delta }) {
    return `${a11yItemName} is moved to position, ${index + 1 + delta} of ${maxLength}. Press Space to confirm new position, Escape to cancel.`;
  },
  CONFIRM: function({ a11yItemName}) {
    return `${a11yItemName} is successfully repositioned.`;
  },
  CANCEL: function({ a11yItemName }) {
    return `Cancelling ${a11yItemName} repositioning`;
  }
}

Visual Indicator

• handleVisualClass This class will be added to the sortable-handle during ACTIVATE and MOVE operations. This allows you to add custom styles such as visual arrows via pseudo classes.

• itemVisualClass This class will be added to the sortable-item during ACTIVATE and MOVE operations. The default class added is is-activated. This is needed to creating a visual indicator that mimics focus b/c the native focus is on the container.

Testing

ember-sortable exposes some acceptance test helpers:

• drag: Drags elements by an offset specified in pixels.
• reorder: Reorders elements to the specified state.
• keyboard: Keycode constants for quick.

To include them in your application, you can import them:

import { 
  drag, reorder,
  ENTER_KEY_CODE,
  SPACE_KEY_CODE,
  ESCAPE_KEY_CODE,
  ARROW_KEY_CODES,
} from 'ember-sortable/test-support';

Examples

Reorder

await reorder('mouse', '[data-test-vertical-demo-handle]', ...order);

Drag

await drag('mouse', '[data-test-scrollable-demo-handle] .handle', () => {
  return { dy: itemHeight() * 2 + 1, dx: undefined };
});

Keyboard

await triggerKeyEvent('[data-test-vertical-demo-handle]', 'keydown', ENTER_KEY_CODE);

Migrating

v3 -> v4

None, just make sure Node v14+ and Ember is v3.24+. Although older versions might work, but are no longer tested against. Specifically ember-modifier dropped support for older versions of Ember.

v2 -> v3

The component versions have been removed and you must use the modifier. The modifier version does not support groupModel, use the currying of the fn helper.

v1 -> v2

If you are migrating from 1.x.x to 2.x.x, For components, please read this migration guide. For modifiers, please read this migration guide.

Developing

Setup

$ git clone [email protected]:adopted-ember-addons/ember-sortable
$ cd ember-sortable
$ ember install

Dev Server

$ ember serve

Running Tests

$ npm test

Publishing Demo

$ make demo