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HTML5 - Drag & Drop




By @islamzatary

List of Advanced HTML5 Topics:


Drag & Drop (DnD)

For years, we've been using libraries like JQuery and Dojo to simplify complex UI elements like animations, rounded corners, and drag and drop.
DnD: Is a first class citizen in HTML5!

Can I use Drag & Drop

Creating draggable content

New attribute called draggable.
Set the draggable=true attribute on the element you want to make moveable.
Just about anything can be drag-enabled, including images, links, files, or other DOM nodes.
most browsers, text selections, img elements, and anchor elements with an href attribute are draggable by default.

Drag & Drop

which can be dropped in the address bar, a element, or even the desktop.

If you want to enable other types of content to be draggable, you'll need to leverage the HTML5 DnD APIs.

Listening for Dragging Events:

dragstart
drag
dragenter
dragleave
dragover
drop
dragend

Drag & Drop

The target is the drop zone (or set of drop zones) that accepts the data the user is trying to drop. Keep in mind that not all elements can be targets (e.g. images).

1. Starting a Drag (dragstart & dragend).

2. dragenter, dragover, and dragleave

return false vs e.preventDefault()
preventDefault : guaranteeing that the anchor's default behavior will not fire, incase we dragging something like a link

3. Completing a Drag

To process the actual drop, add an event listener for the drop and dragendevents.

The DataTransfer object

It holds the piece of data sent in a drag action.

dataTransfer is set in the dragstart event and read/handled in the drop event. Calling e.dataTransfer.setData(format, data) will set the object's content to the mimetype and data payload passed as arguments.
getData(format) for fetching the drag data by mimetype.

Dragging properties

1. dataTransfer.effectAllowed
Restricts what 'type of drag' the user can perform on the element, to initialize the dropEffect during the dragenter and dragover events.
values: none, copy, copyLink, copyMove, link, linkMove, move, all, and uninitialized.

2. dataTransfer.dropEffect
Controls the feedback that the user is given during the dragenter and dragover events.
When the user hovers over a target element, the browser's cursor will indicate what type of operation is going to take place (e.g. a copy, a move, etc.)
values: none, copy, link, move.

Dragging properties

3. e.dataTransfer.setDragImage(imgElement, x, y)
by this property, you can optionally set a drag icon.

Dragging Files
Instead of using dataTransfer.getData() to access the files, their data will be contained in the dataTransfer.files property

HTML5's DnD model is complicated compared to other solutions like JQuery UI

Complete Example

HTML5 - Drag & Drop




Practical



Wrapping up







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by @islamzatary