Sortable plugins are plugins that can be directly mounted to the Sortable class. They are a powerful way of modifying the default behaviour of Sortable beyond what simply using events alone allows. To mount your plugin to Sortable, it must pass a constructor function to the Sortable.mount function. This constructor function will be called (with the new keyword in front of it) whenever a Sortable instance with your plugin enabled is initialized. The constructor function will be called with the parameters sortable and el, which is the HTMLElement that the Sortable is being initialized on. This means that there will be a new instance of your plugin each time it is enabled in a Sortable.

sortable: Sortable — The sortable that the plugin is being initialized on

el: HTMLElement — The element that the sortable is being initialized on

options: Object — The options object that the user has passed into Sortable (not merged with defaults yet)

The constructor function passed to Sortable.mount may contain several static properties and methods. The following static properties may be defined:

pluginName: String (Required) The name of the option that the user will use in their sortable's options to enable the plugin. Should start with a lower case and be camel-cased. For example: 'multiDrag'. This is also the property name that the plugin's instance will be under in a sortable instance (ex. sortableInstance.multiDrag).

utils: Object Object containing functions that will be added to the Sortable.utils static object on the Sortable class.

eventOptions(eventName: String): Function A function that is called whenever Sortable fires an event. This function should return an object to be combined with the event object that Sortable will emit. The function will be called in the context of the instance of the plugin on the Sortable that is firing the event (ie. the this keyword will be the plugin instance).

initializeByDefault: Boolean Determines whether or not the plugin will always be initialized on every new Sortable instance. If this option is enabled, it does not mean that by default the plugin will be enabled on the Sortable - this must still be done in the options via the plugin's pluginName, or it can be enabled by default if your plugin specifies it's pluginName as a default option that is truthy. Since the plugin will already be initialized on every Sortable instance, it can also be enabled dynamically via sortableInstance.option('pluginName', true). It is a good idea to have this option set to false if the plugin modifies the behaviour of Sortable in such a way that enabling or disabling the plugin dynamically could cause it to break. Likewise, this option should be disabled if the plugin should only be instantiated on Sortables in which that plugin is enabled. This option defaults to true.

optionListeners: Object An object that may contain event listeners that are fired when a specific option is updated. These listeners are useful because the user's provided options are not necessarily unchanging once the plugin is initialized, and could be changed dynamically via the option() method. The listener will be fired in the context of the instance of the plugin that it is being changed in (ie. the this keyword will be the instance of your plugin). The name of the method should match the name of the option it listens for. The new value of the option will be passed in as an argument, and any returned value will be what the option is stored as. If no value is returned, the option will be stored as the value the user provided.

Example:

Plugin.name = 'generateTitle';
Plugin.optionListeners = {
	// Listen for option 'generateTitle'
	generateTitle: function(title) {
		// Store the option in all caps
		return title.toUpperCase();

		// OR save it to this instance of your plugin as a private field.
		// This way it can be accessed in events, but will not modify the user's options.
		this.titleAllCaps = title.toUpperCase();
	}
};

Plugins may have custom default options or may override the defaults of other options. In order to do this, there must be a defaults object on the initialized plugin. This can be set in the plugin's prototype, or during the initialization of the plugin (when the el is available). For example:

function myPlugin(sortable, el, options) {
	this.defaults = {
		color: el.style.backgroundColor
	};
}

Sortable.mount(myPlugin);

The events will be fired in the context of their own parent object (ie. context is not changed), however the plugin instance's Sortable instance is available under this.sortable. Likewise, the options are available under this.options.

The following table contains details on the events that a plugin may handle in the prototype of the plugin's constructor function.

Normally, an event will only be fired in a plugin if the plugin is enabled on the Sortable from which the event is being fired. However, it sometimes may be desirable for a plugin to listen in on an event from Sortables in which it is not enabled on. This is possible with global events. For an event to be global, simply add the suffix 'Global' to the event's name (casing matters) (eg. dragStartGlobal). Please note that your plugin must be initialized on any Sortable from which it expects to recieve events, and that includes global events. In other words, you will want to keep the initializeByDefault option as it's default true value if your plugin needs to recieve events from Sortables it is not enabled on. Please also note that if both normal and global event handlers are set, the global event handler will always be fired before the regular one.

An object with the following properties is passed as an argument to each plugin event when it is fired.

dragEl: HTMLElement — The element being dragged

parentEl: HTMLElement — The element that the dragged element is currently in

ghostEl: HTMLElement|undefined — If using fallback, the element dragged under the cursor (undefined until after dragStarted plugin event)

rootEl: HTMLElement — The element that the dragged element originated from

nextEl: HTMLElement — The original next sibling of dragEl

cloneEl: HTMLElement|undefined — The clone element (undefined until after setupClone plugin event)

cloneHidden: Boolean — Whether or not the clone is hidden

dragStarted: Boolean — Boolean indicating whether or not the dragStart event has fired

putSortable: Sortable|undefined — The element that dragEl is dragged into from it's root, otherwise undefined

activeSortable: Sortable — The active Sortable instance

originalEvent: Event — The original HTML event corresponding to the Sortable event

oldIndex: Number — The old index of dragEl

oldDraggableIndex: Number — The old index of dragEl, only counting draggable elements

newIndex: Number — The new index of dragEl

newDraggableIndex: Number — The new index of dragEl, only counting draggable elements

cloneNowHidden() — Function to be called if the plugin has hidden the clone

cloneNowShown() — Function to be called if the plugin has shown the clone

hideGhostForTarget() — Hides the fallback ghost element if CSS pointer-events are not available. Call this before using document.elementFromPoint at the mouse position.

unhideGhostForTarget() — Unhides the ghost element. To be called after hideGhostForTarget().

dispatchSortableEvent(eventName: String) — Function that can be used to emit an event on the current sortable while sorting, with all usual event properties set (eg. indexes, rootEl, cloneEl, originalEvent, etc.).

This event is passed to dragover events, and extends the normal event object.

isOwner: Boolean — Whether or not the dragged over sortable currently contains the dragged element

axis: String — Direction of the dragged over sortable, 'vertical' or 'horizontal'

revert: Boolean — Whether or not the dragged element is being reverted to it's original position from another position

dragRect: DOMRect — DOMRect of the dragged element

targetRect: DOMRect — DOMRect of the target element

canSort: Boolean — Whether or not sorting is enabled in the dragged over sortable

fromSortable: Sortable — The sortable that the dragged element is coming from

target: HTMLElement — The sortable item that is being dragged over

onMove(target: HTMLElement, after: Boolean): Boolean|Number — Calls the onMove function the user specified in the options

changed() — Fires the onChange event with event properties preconfigured

completed(insertion: Boolean) — Should be called when dragover has "completed", meaning bubbling should be stopped. If insertion is true, Sortable will treat it as if the dragged element was inserted into the sortable, and hide/show clone, set ghost class, animate, etc.