<drag-dropzone>

$ bower install --save drag-dropzone

What's cool

• Includes and implements dragDropzoneBehavior which can be attached to any element. You can either use the element itself, or just the behavior.
• Lightweight, has 0 dependencies
• Handles both Files and draggable DOMElements
• Handles paste as well

Basic Usage

<drag-dropzone></drag-dropzone>

<script>
  document.querySelector('drag-dropzone').addEventListener('item-dropped', e => {
    console.log(e.detail); // Logs items and drop position
  })
</script>

Usage with DOM elements

Just make sure your DOM elements declare the following:

• allow-drop=true
• type="DOMElement"
• The data you want to receive when it's dropped on the drop zone.

<div ondragstart="drag(event)" draggable="true">Draggable thingy</div>
<drag-dropzone></drag-dropzone>

<script>
  function drag(e) {
    e.dataTransfer.setData('allow-drop', true);
    e.dataTransfer.setData('type', 'DOMElement');
    e.dataTransfer.setData('data', 'foo-bar');
  }

  document.querySelector('drag-dropzone').addEventListener('item-dropped', e => {
    console.log(e.detail); // Logs items and drop position
  })
</script>

Restricting file types

Set an accept attribute with a comma-separated String of the types it should accept.

<drag-dropzone accept="application/pdf, image/png"></drag-dropzone>

<script>
  // Assuming you dropped anything other than a PNG or PDF
  document.querySelector('drag-dropzone').addEventListener('item-error', e => {
    console.log(e.detail.text); // Logs 'Unsupported file type'
  })
</script>

Using the Behavior

The element includes dragDropzoneBehavior which can be easily attached to any element.

<dom-module id="my-element">
  <template>
    <style>
      :host {
        display: block;
        text-align: center;
        padding: 1em;
      }
    </style>
    <label hidden$="[[!itemDragged]]">Drop Here</label>
  </template>

  <script>
    Polymer({

      is: 'my-element',

      behaviors: [
        dragDropBehavior
      ]
    });
  </script>
</dom-module>

Gotchas

The paste event is attached on window.

If you have more than one dropzone per page, the item-dropped event will be fired from all <drag-dropzone> elements when pasting.

In that case it makes sense to debounce the event so you handle it only once.

document.querySelector('drag-dropzone').addEventListener('item-dropped', e => {
  debounce(() => {
    // handle event
  }, 200);
})

There's an open Issue for the paste issues.

Running Tests

$ npm install -g polymer-cli
$ polymer test

Authors

• Nicholas Kyriakides, @nicholaswmin, nik.kyriakides@gmail.com

License

Copyright (c) 2017 The Profs LTD

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.