readme.markdown

Dragula

Drag and drop so simple it hurts

Browser support includes every sane browser and IE7+. _{(Granted you polyfill the functional Array methods in ES5)}

Demo

Try out the demo!

Inspiration

Have you ever wanted a drag and drop library that just works? That doesn't just depend on bloated frameworks, that has great support? That actually understands where to place the elements when they are dropped? That doesn't need you to do a zillion things to get it to work? Well, so did I!

Features

• Super easy to set up
• No bloated dependencies
• Figures out sort order on its own
• A shadow where the item would be dropped offers visual feedback
• Touch events!

Install

You can get it on npm.

npm install dragula --save

Or bower, too. _{(note that it's called dragula.js in bower)}

bower install dragula.js --save

Usage

Dragula provides the easiest possible API to make drag and drop a breeze in your applications.

dragula(containers?, options?)

By default, dragula will allow the user to drag an element in any of the containers and drop it in any other container in the list. If the element is dropped anywhere that's not one of the containers, the event will be gracefully cancelled according to the revertOnSpill and removeOnSpill options.

Note that dragging is only triggered on left clicks, and only if no meta keys are pressed. Clicks on buttons and anchor tags are ignored, too.

The example below allows the user to drag elements from left into right, and from right into left.

dragula([document.querySelector('#left'), document.querySelector('#right')]);

You can also provide an options object. Here's an overview of the default values.

dragula(containers, {
  isContainer: function (el) {
    return false; // only elements in drake.containers will be taken into account
  },
  moves: function (el, container, handle) {
    return true; // elements are always draggable by default
  },
  accepts: function (el, target, source, sibling) {
    return true; // elements can be dropped in any of the `containers` by default
  },
  invalid: function (el, target) { // prevent buttons and anchor tags from starting a drag
    return el.tagName === 'A' || el.tagName === 'BUTTON';
  },
  direction: 'vertical', // Y axis is considered when determining where an element would be dropped
  copy: false,           // elements are moved by default, not copied
  revertOnSpill: false,  // spilling will put the element back where it was dragged from, if this is true
  removeOnSpill: false,  // spilling will `.remove` the element, if this is true
  delay: false           // enable regular clicks by setting to true or a number of milliseconds
});

You can omit the containers argument and add containers dynamically later on.

var drake = dragula({
  copy: true
});
drake.containers.push(container);

You can also set the containers from the options object.

var drake = dragula({ containers: containers });

And you could also not set any arguments, which defaults to a drake without containers and with the default options.

var drake = dragula();

The options are detailed below.

options.containers

Setting this option is effectively the same as passing the containers in the first argument to dragula(containers, options).

options.isContainer

Besides the containers that you pass to dragula, or the containers you dynamically push or unshift from drake.containers, you can also use this method to specify any sort of logic that defines what is a container for this particular drake instance.

The example below dynamically treats all DOM elements with a CSS class of dragula-container as dragula containers for this drake.

var drake = dragula({
  isContainer: function (el) {
    return el.classList.contains('dragula-container');
  }
});

options.moves

You can define a moves method which will be invoked with (el, container, handle) whenever an element is clicked. If this method returns false, a drag event won't begin, and the event won't be prevented either. The handle element will be the original click target, which comes in handy to test if that element is an expected "drag handle".

options.accepts

You can set accepts to a method with the following signature: (el, target, source, sibling). It'll be called to make sure that an element el, that came from container source, can be dropped on container target before a sibling element. The sibling can be null, which would mean that the element would be placed as the last element in the container. Note that if options.copy is set to true, el will be set to the copy, instead of the originally dragged element.

Also note that the position where a drag starts is always going to be a valid place where to drop the element, even if accepts returned false for all cases.

options.copy

If copy is set to true, items will be copied rather than moved. This implies the following differences:

Event	Move	Copy
drag	Element will be concealed from source	Nothing happens
drop	Element will be moved into target	Element will be cloned into target
remove	Element will be removed from DOM	Nothing happens
cancel	Element will stay in source	Nothing happens

options.revertOnSpill

By default, spilling an element outside of any containers will move the element back to the drop position previewed by the feedback shadow. Setting revertOnSpill to true will ensure elements dropped outside of any approved containers are moved back to the source element where the drag event began, rather than stay at the drop position previewed by the feedback shadow.

options.removeOnSpill

By default, spilling an element outside of any containers will move the element back to the drop position previewed by the feedback shadow. Setting removeOnSpill to true will ensure elements dropped outside of any approved containers are removed from the DOM. Note that remove events won't fire if copy is set to true.

options.direction

When an element is dropped onto a container, it'll be placed near the point where the mouse was released. If the direction is 'vertical', the default value, the Y axis will be considered. Otherwise, if the direction is 'horizontal', the X axis will be considered.

options.delay

Number of milliseconds during which clicks where the mouse button is released will be treated as regular clicks instead of very short lived drags. When delay is set to true, a default of 300 milliseconds is used. Defaults to false.

options.invalid

You can provide an invalid method with a (el, target) signature. This method should return true for elements that shouldn't trigger a drag. Here's the default implementation, which prevents drags originating from anchor elements and buttons.

function invalidTarget (el) {
  return el.tagName === 'A' || el.tagName === 'BUTTON';
}

Note that invalid will be invoked on the DOM element that was clicked and every parent up to immediate children of a drake container.

API

The dragula method returns a tiny object with a concise API. We'll refer to the API returned by dragula as drake.

drake.addContainer(container)

DEPRECATED. Use drake.containers instead. Adds a container to the containers collection. It can be a single DOM element or an array.

drake.removeContainer(container)

DEPRECATED. Use drake.containers instead. Removes a container from the containers collection. It can be a single DOM element or an array.

drake.containers

This property contains the collection of containers that was passed to dragula when building this drake instance. You can push more containers and splice old containers at will.

drake.dragging

This property will be true whenever an element is being dragged.

drake.start(item)

Enter drag mode without a shadow. This method is most useful when providing complementary keyboard shortcuts to an existing drag and drop solution. Even though a shadow won't be created at first, the user will get one as soon as they click on item and start dragging it around. Note that if they click and drag something else, .end will be called before picking up the new item.

drake.end()

Gracefully end the drag event as if using the last position marked by the preview shadow as the drop target. The proper cancel or drop event will be fired, depending on whether the item was dropped back where it was originally lifted from (which is essentially a no-op that's treated as a cancel event).

drake.cancel(revert)

If an element managed by drake is currently being dragged, this method will gracefully cancel the drag action. You can also pass in revert at the method invocation level, effectively producing the same result as if revertOnSpill was true.

Note that a "cancellation" will result in a cancel event only in the following scenarios.

• revertOnSpill is true
• Drop target (as previewed by the feedback shadow) is the source container and the item is dropped in the same position where it was originally dragged from

drake.remove()

If an element managed by drake is currently being dragged, this method will gracefully remove it from the DOM.

drake.on (Events)

The drake is an event emitter. The following events can be tracked using drake.on(type, listener):

Event Name	Listener Arguments	Event Description
drag	el, container	el was lifted from container
dragend	el	Dragging event for el ended with either cancel, remove, or drop
drop	el, container, source	el was dropped into container, and originally came from source
cancel	el, container	el was being dragged but it got nowhere and went back into container, its last stable parent
remove	el, container	el was being dragged but it got nowhere and it was removed from the DOM. Its last stable parent was container.
shadow	el, container	el, the visual aid shadow, was moved into container. May trigger many times as the position of el changes, even within the same container
cloned	clone, original	DOM element original was cloned as clone. Triggers for mirror images and when copy: true

drake.destroy()

Removes all drag and drop events used by dragula to manage drag and drop between the containers. If .destroy is called while an element is being dragged, the drag will be effectively cancelled.

License

MIT