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https://github.com/schne324/dragon-drop

Accessible drag and drop list reorder module
https://github.com/schne324/dragon-drop

a11y accessible drag-and-drop dragon-drop

Last synced: 16 days ago
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Accessible drag and drop list reorder module

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README 

        
# Dragon Drop



[![CircleCI](https://circleci.com/gh/schne324/dragon-drop.svg?style=svg)](https://circleci.com/gh/schne324/dragon-drop)



Keyboard/assistive technology accessible drag-and-drop reorder list.



Dragon Drop



## Demo



http://schne324.github.io/dragon-drop/demo/






## Enter the dragon...



For an in-depth look at dragon drop see the [smashing magazine article on dragon drop](https://www.smashingmagazine.com/2018/01/dragon-drop-accessible-list-reordering/)



## Installation



## npm

```bash

$ npm install drag-on-drop

```



### bower

```bash

$ bower install drag-on-drop

```



## Usage



### Browserify/Webpack



```js

import DragonDrop from 'drag-on-drop';



const dragon = new DragonDrop(container, options);

```



### In the browser



```js

const DragonDrop = window.DragonDrop;

const dragon = new DragonDrop(container, options);

```



### React



Although a DragonDrop react component doesn't exist (yet), it can be used _with_ react:



```js

class App extends Component {

  componentDidMount() {

    this.setState({

      dragonDrop: new DragonDrop(this.dragon)

    });

  }



  componentDidUpdate() {

    const { dragonDrop } = this.state;

    // this public method allows dragon drop to

    // reassess the updated items and handles

    dragonDrop.initElements(this.dragon);

  }



  render() {

    return (

      
     this.dragon = el}>

            
  • 

              

              Item 1

            
    • 

            
  • 

              

              Item 2

            
    • 

          


    );

  }

}

```

[Full example](https://codepen.io/schne324/pen/dZOGeG)



**NOTE** usage with react is not exactly ideal because DragonDrop uses normal DOM events not picked up by react (react doesn't know about the reordering).



### CDN (unpkg)



https://unpkg.com/drag-on-drop



## API



### `new DragonDrop(container, [options])`



#### `container` _HTMLElement|Array_ (required)



Either a single container element or an array of container elements.



#### `options` _Object_ (optional)



##### `item` _String_



The selector for the drag items (qualified within container). Defaults to

```js

'li'

```



##### `handle` _String_



The selector for the keyboard handle (qualified within the container and the selector provided for `item`). If set to `false`, the entire item will be used as the handle. Defaults to

```ks

'button'

```



##### `activeClass` _String_



The class to be added to the item being dragged. Defaults to



```js

'dragon-active'

```



##### `inactiveClass` _String_



The class to be added to all of the other items when an item is being dragged. Defaults



```js

'dragon-inactive'

```



##### `nested` _Boolean_



Set to true if nested lists are being used (click and keydown events will not bubble up (`e.stopPropagation()` will be applied)). For nested lists, you MUST pass `DragonDrop` an array of containers as the 1st parameter (see example below).



__NOTE:__ *there is a 99% chance that you'll need to use [:scope selectors](https://developer.mozilla.org/en-US/docs/Web/CSS/:scope) to target only a given list's items (because dragon drop would otherwise include the sub list's items for example). Using `:scope` selectors will allow you to target direct descendant children (example: `:scope > li`).*



```js

const lists = Array.from(document.querySelectorAll('.dragon-list'));

const dragons = new DragonDrop(lists, {

  nested: true,

  handle: false,

  item: ':scope > li' // IMPORTANT! a selector that targets only a single list's items

});

const [ topLevel, sublist1, sublist2 ] = dragons;



topLevel.on('grabbed', () => console.log('top-most container item grabbed'));

sublist1.on('grabbed', () => console.log('sublist 1 item grabbed'));

sublist2.on('grabbed', () => console.log('sublist 1 item grabbed'));

```



##### `dragulaOptions` _Object_



An options object passed through to dragula.



__NOTE__: `dragulaOptions.moves` will be ignored given a DragonDrop instance with `nested: false` and a truthy `handle`



__NOTE__: `dragulaOptions.moves` AND `dragulaOptions.accepts` will be ignored given a DragonDrop instance with `nested: true`



##### `announcement` _Object_



The live region announcement configuration object containing the following properties:



###### `grabbed` _Function_



The function called when an item is picked up. The currently grabbed element along with an array of all items are passed as arguments respectively. The function should return a string of text to be announced in the live region. Defaults to



```js

el => `Item ${el.innerText} grabbed`

```



###### `dropped` _Function_



The function called when an item is dropped. The newly dropped item along with an array of all items are passed as arguments respectively. The function should return a string of text to be announced in the live region. Defaults to



```js

el => `Item ${el.innerText} dropped`

```



###### `reorder` _Function_



The function called when the list has been reordered. The newly dropped item along with an array of items are passed as arguments respectively. The function should return a string of text to be announced in the live region. Defaults to



```js

(el, items) => {

  const pos = items.indexOf(el) + 1;

  const text = el.innerText;

  return `The list has been reordered, ${text} is now item ${pos} of ${items.length}`;

}

```



###### `cancel` _Function_



The function called when the reorder is cancelled (via ESC). No arguments passed in. Defaults to



```js

() => 'Reordering cancelled'

```



##### `liveRegion` _Object_



Attributes that can be overridden in on the live region:



###### `ariaLive` _string_



Optional ariaLive attribute to be passed to the live region. Valid values are "off", "polite", or "assertive". Default is "assertive".



###### `ariaRelevant` string



Optional ariaRelevant attribute to be passed to the live region. Valid values are "additions", "removals", "text", and "all". Default is "additions".



###### `ariaAtomic` boolean



Optional ariaAtomic attribute to be passed to the live region. Default is "true".



## Properties



```js

const dragonDrop = new DragonDrop(container);

```

### `dragonDrop.items` _Array_



An array of each of the sortable item element references.



### `dragonDrop.handles` _Array_



An array of each of the handle item element references. If instance doesn't have handles, this will be identical to `dragonDrop.items`.



### `dragonDrop.dragula`



A direct handle on the `dragula` instance created by `dragonDrop`



### Example with options



```js

const list = document.getElementById('dragon-list');

const dragonDrop = new DragonDrop(list, {

  item: 'li',

  handle: '.handle',

  announcement: {

    grabbed: el => `The dragon has grabbed ${el.innerText}`,

    dropped: el => `The dragon has dropped ${el.innerText}`,

    reorder: (el, items) => {

      const pos = items.indexOf(el) + 1;

      const text = el.innerText;

      return `The dragon's list has been reordered, ${text} is now item ${pos} of ${items.length}`;

    },

    cancel: 'The dragon cancelled the reorder'

  }

});

```



## Events



Dragon drop emit events when important stuff happens.



### `dragonDrop.on('grabbed', callback)`



Fires when an item is grabbed (with keyboard or mouse). The callback is passed the container along with the grabbed item.



### `dragonDrop.on('dropped', callback)`



Fires when an item is dropped (with keyboard or mouse). The callback is passed the container and the grabbed item.



### `dragonDrop.on('reorder', callback)`



Fires when a list is reordered. The callback is passed the container along with the item.



### `dragonDrop.on('cancel', callback)`



Fires when a user cancels reordering with the escape key. The callback is passed the keydown event that triggered the cancel.



### Example use of events



```js

dragonDrop

  .on('grabbed', (container, item) => console.log(`Item ${item.innerText} grabbed`))

  .on('dropped', (container, item) => console.log(`Item ${item.innerText} dropped`))

  .on('reorder', (container, item) => console.log(`Reorder: ${item.innerText} has moved`))

  .on('cancel', (e) => {

    console.log('Reordering cancelled');

    e.preventDefault();

  });

```



**NOTE** for mouse drag/drop event hooks the `dragula` property is exposed for dragula's events

```js

dragonDrop.dragula.on('drop', ...);

```



## Methods



### `dragonDrop.initElements(container)`



Reinitialises the list, so that newly added items can be dragged. You can do this automatically with a `MutationObserver`:



```js

const observer = new MutationObserver(() => dragonDrop.initElements(container));

observer.observe(container, {childList: true});

```



## Debugging



Set the following localStorage option to debug dragonDrop



```js

localStorage.debug = 'drag-on-drop:*';

```



## Notes on accessibility



There are certain things that are left up to the discretion of the implementer.  This is to keep `DragonDrop` less opinionated on some of the gray areas of a11y. The [demos](http://schne324.github.io/dragon-drop/demo/) show a few different approaches on associating help text with DragonDrop:



1. __Recommended__ `aria-describedby` on each control (item, or if applicable, handle). This is the safest/test approach because it guarantees that AT users will receive the instructions. [Demo of this approach](https://schne324.github.io/dragon-drop/demo/index.html#bands-head)

1. __Recommended__ `aria-labelledby` on the container/list element.  With this approach, where supported, will announce the instructions whenever the AT users enters the list (which is less verbose than the above). [Demo of this approach](https://schne324.github.io/dragon-drop/demo/index.html#schedule-head)

1. __Not recommended__`aria-describedby` on the container/list element. This approach, where supported, will only announce the instructions if the screen reader user traverses to the actual list element. [Demo of this approach](https://schne324.github.io/dragon-drop/demo/index.html#nested)



For more information regarding accessibility you can read an [accessibility review of dragon drop](https://github.com/schne324/dragon-drop/issues/6) initiated by Drupal.



## Thanks!



A special thanks to Aaron Pearlman for the logo.



Another special thanks to contributors/maintainers of [dragula](https://github.com/bevacqua/dragula) which is used for all of the mouse behavior/interaction for dragon drop!