Class

ViewCollection (ui)

@ckeditor/ckeditor5-ui/src/viewcollection

class

Collects View instances.

const parentView = new ParentView( locale );
const collection = new ViewCollection( locale );

collection.setParent( parentView.element );

const viewA = new ChildView( locale );
const viewB = new ChildView( locale );

View collection renders and manages view elements:

collection.add( viewA );
collection.add( viewB );

console.log( parentView.element.firsChild ); // -> viewA.element
console.log( parentView.element.lastChild ); // -> viewB.element

It propagates DOM events too:

// Delegate #click and #keydown events from viewA and viewB to the parentView.
collection.delegate( 'click' ).to( parentView );

parentView.on( 'click', ( evt ) => {
	console.log( `${ evt.source } has been clicked.` );
} );

// This event will be delegated to the parentView.
viewB.fire( 'click' );

Note: A view collection can be used directly in the definition of a template.

Filtering

Type parameters

Properties

  • readonly inherited

    first : null | T

    Returns the first item from the collection or null when collection is empty.

  • id : string | undefined

  • readonly inherited

    last : null | T

    Returns the last item from the collection or null when collection is empty.

  • readonly inherited

    length : number

    The number of items available in the collection.

  • private

    _parentElement : null | HTMLElement | DocumentFragment

    A parent element within which child views are rendered and managed in DOM.

Methods

  • constructor( initialItems )

    Creates a new instance of the ViewCollection.

    Type parameters

    TView : extends [object Object] = default

    Parameters

    initialItems : Iterable<TView>

    The initial items of the collection.

    Defaults to []

  • inherited

    Symbol.iterator() → Iterator<TView, any, undefined>

    Iterable interface.

    Returns

    Iterator<TView, any, undefined>
  • inherited

    add( item, [ index ] ) → ViewCollection<TView>

    Adds an item into the collection.

    If the item does not have an id, then it will be automatically generated and set on the item.

    Parameters

    item : TView
    [ index ] : number

    The position of the item in the collection. The item is pushed to the collection when index not specified.

    Returns

    ViewCollection<TView>

    Fires

  • inherited

    addMany( items, [ index ] ) → ViewCollection<TView>

    Adds multiple items into the collection.

    Any item not containing an id will get an automatically generated one.

    Parameters

    items : Iterable<TView>
    [ index ] : number

    The position of the insertion. Items will be appended if no index is specified.

    Returns

    ViewCollection<TView>

    Fires

  • inherited

    bindTo( externalCollection ) → CollectionBindToChain<S, TView>

    Binds and synchronizes the collection with another one.

    The binding can be a simple factory:

    class FactoryClass {
    	public label: string;
    
    	constructor( data: { label: string } ) {
    		this.label = data.label;
    	}
    }
    
    const source = new Collection<{ label: string }>( { idProperty: 'label' } );
    const target = new Collection<FactoryClass>();
    
    target.bindTo( source ).as( FactoryClass );
    
    source.add( { label: 'foo' } );
    source.add( { label: 'bar' } );
    
    console.log( target.length ); // 2
    console.log( target.get( 1 ).label ); // 'bar'
    
    source.remove( 0 );
    console.log( target.length ); // 1
    console.log( target.get( 0 ).label ); // 'bar'
    

    or the factory driven by a custom callback:

    class FooClass {
    	public label: string;
    
    	constructor( data: { label: string } ) {
    		this.label = data.label;
    	}
    }
    
    class BarClass {
    	public label: string;
    
    	constructor( data: { label: string } ) {
    		this.label = data.label;
    	}
    }
    
    const source = new Collection<{ label: string }>( { idProperty: 'label' } );
    const target = new Collection<FooClass | BarClass>();
    
    target.bindTo( source ).using( ( item ) => {
    	if ( item.label == 'foo' ) {
    		return new FooClass( item );
    	} else {
    		return new BarClass( item );
    	}
    } );
    
    source.add( { label: 'foo' } );
    source.add( { label: 'bar' } );
    
    console.log( target.length ); // 2
    console.log( target.get( 0 ) instanceof FooClass ); // true
    console.log( target.get( 1 ) instanceof BarClass ); // true
    

    or the factory out of property name:

    const source = new Collection<{ nested: { value: string } }>();
    const target = new Collection<{ value: string }>();
    
    target.bindTo( source ).using( 'nested' );
    
    source.add( { nested: { value: 'foo' } } );
    source.add( { nested: { value: 'bar' } } );
    
    console.log( target.length ); // 2
    console.log( target.get( 0 ).value ); // 'foo'
    console.log( target.get( 1 ).value ); // 'bar'
    

    It's possible to skip specified items by returning null value:

    const source = new Collection<{ hidden: boolean }>();
    const target = new Collection<{ hidden: boolean }>();
    
    target.bindTo( source ).using( item => {
    	if ( item.hidden ) {
    		return null;
    	}
    
    	return item;
    } );
    
    source.add( { hidden: true } );
    source.add( { hidden: false } );
    
    console.log( source.length ); // 2
    console.log( target.length ); // 1
    

    Note: clear can be used to break the binding.

    Type parameters

    S : extends Record<string, any>

    The type of externalCollection element.

    Parameters

    externalCollection : Collection<S>

    A collection to be bound.

    Returns

    CollectionBindToChain<S, TView>

    The binding chain object.

  • inherited

    clear() → void

    Removes all items from the collection and destroys the binding created using bindTo.

    Returns

    void

    Fires

  • delegate( events ) → EmitterMixinDelegateChain

    Delegates selected events coming from within views in the collection to any Emitter.

    For the following views and collection:

    const viewA = new View();
    const viewB = new View();
    const viewC = new View();
    
    const views = parentView.createCollection();
    
    views.delegate( 'eventX' ).to( viewB );
    views.delegate( 'eventX', 'eventY' ).to( viewC );
    
    views.add( viewA );
    

    the eventX is delegated (fired by) viewB and viewC along with customData:

    viewA.fire( 'eventX', customData );
    

    and eventY is delegated (fired by) viewC along with customData:

    viewA.fire( 'eventY', customData );
    

    See delegate.

    Parameters

    events : Array<string>

    View event names to be delegated to another Emitter.

    Returns

    EmitterMixinDelegateChain

    Object with to property, a function which accepts the destination of delegated events.

  • destroy() → void

    Destroys the view collection along with child views. See the view destroy method.

    Returns

    void
  • inherited

    filter( callback, [ ctx ] ) → Array<TView>

    Returns an array with items for which the callback returned a true value.

    Parameters

    callback : ( TView, number ) => boolean
    [ ctx ] : any

    Context in which the callback will be called.

    Returns

    Array<TView>

    The array with matching items.

  • inherited

    find( callback, [ ctx ] ) → undefined | TView

    Finds the first item in the collection for which the callback returns a true value.

    Parameters

    callback : ( TView, number ) => boolean
    [ ctx ] : any

    Context in which the callback will be called.

    Returns

    undefined | TView

    The item for which callback returned a true value.

  • inherited

    fire( eventOrInfo, args ) → GetEventInfo<TEvent>[ 'return' ]

    Fires an event, executing all callbacks registered for it.

    The first parameter passed to callbacks is an EventInfo object, followed by the optional args provided in the fire() method call.

    Type parameters

    TEvent : extends BaseEvent

    The type describing the event. See BaseEvent.

    Parameters

    eventOrInfo : GetNameOrEventInfo<TEvent>

    The name of the event or EventInfo object if event is delegated.

    args : TEvent[ 'args' ]

    Additional arguments to be passed to the callbacks.

    Returns

    GetEventInfo<TEvent>[ 'return' ]

    By default the method returns undefined. However, the return value can be changed by listeners through modification of the evt.return's property (the event info is the first param of every callback).

  • inherited

    forEach( callback, [ ctx ] ) → void

    Performs the specified action for each item in the collection.

    Parameters

    callback : ( TView, number ) => unknown
    [ ctx ] : any

    Context in which the callback will be called.

    Returns

    void
  • inherited

    get( idOrIndex ) → null | TView

    Gets an item by its ID or index.

    Parameters

    idOrIndex : string | number

    The item ID or index in the collection.

    Returns

    null | TView

    The requested item or null if such item does not exist.

  • inherited

    getIndex( itemOrId ) → number

    Gets an index of an item in the collection. When an item is not defined in the collection, the index will equal -1.

    Parameters

    itemOrId : string | TView

    The item or its ID in the collection.

    Returns

    number

    The index of a given item.

  • inherited

    has( itemOrId ) → boolean

    Returns a Boolean indicating whether the collection contains an item.

    Parameters

    itemOrId : string | TView

    The item or its ID in the collection.

    Returns

    boolean

    true if the collection contains the item, false otherwise.

  • inherited

    listenTo( emitter, event, callback, [ options ] ) → void

    Registers a callback function to be executed when an event is fired in a specific (emitter) object.

    Events can be grouped in namespaces using :. When namespaced event is fired, it additionally fires all callbacks for that namespace.

    // myEmitter.on( ... ) is a shorthand for myEmitter.listenTo( myEmitter, ... ).
    myEmitter.on( 'myGroup', genericCallback );
    myEmitter.on( 'myGroup:myEvent', specificCallback );
    
    // genericCallback is fired.
    myEmitter.fire( 'myGroup' );
    // both genericCallback and specificCallback are fired.
    myEmitter.fire( 'myGroup:myEvent' );
    // genericCallback is fired even though there are no callbacks for "foo".
    myEmitter.fire( 'myGroup:foo' );
    

    An event callback can stop the event and set the return value of the fire method.

    Type parameters

    TEvent : extends BaseEvent

    The type describing the event. See BaseEvent.

    Parameters

    emitter : Emitter

    The object that fires the event.

    event : TEvent[ 'name' ]

    The name of the event.

    callback : GetCallback<TEvent>

    The function to be called on event.

    [ options ] : GetCallbackOptions<TEvent>

    Additional options.

    Returns

    void
  • inherited

    map( callback, [ ctx ] ) → Array<U>

    Executes the callback for each item in the collection and composes an array or values returned by this callback.

    Type parameters

    U

    The result type of the callback.

    Parameters

    callback : ( TView, number ) => U
    [ ctx ] : any

    Context in which the callback will be called.

    Returns

    Array<U>

    The result of mapping.

  • inherited

    off( event, callback ) → void

    Stops executing the callback on the given event. Shorthand for this.stopListening( this, event, callback ).

    Parameters

    event : string

    The name of the event.

    callback : Function

    The function to stop being called.

    Returns

    void
  • inherited

    on( event, callback, [ options ] ) → void

    Registers a callback function to be executed when an event is fired.

    Shorthand for this.listenTo( this, event, callback, options ) (it makes the emitter listen on itself).

    Type parameters

    TEvent : extends BaseEvent

    The type descibing the event. See BaseEvent.

    Parameters

    event : TEvent[ 'name' ]

    The name of the event.

    callback : GetCallback<TEvent>

    The function to be called on event.

    [ options ] : GetCallbackOptions<TEvent>

    Additional options.

    Returns

    void
  • inherited

    once( event, callback, [ options ] ) → void

    Registers a callback function to be executed on the next time the event is fired only. This is similar to calling on followed by off in the callback.

    Type parameters

    TEvent : extends BaseEvent

    The type descibing the event. See BaseEvent.

    Parameters

    event : TEvent[ 'name' ]

    The name of the event.

    callback : GetCallback<TEvent>

    The function to be called on event.

    [ options ] : GetCallbackOptions<TEvent>

    Additional options.

    Returns

    void
  • remove( subject ) → TView

    Removes a child view from the collection. If the parent element of the collection has been set, the element of the view is also removed in DOM, reflecting the order of the collection.

    See the add method.

    Parameters

    subject : string | number | TView

    The view to remove, its id or index in the collection.

    Returns

    TView

    The removed view.

  • setParent( elementOrDocFragment ) → void

    Sets the parent HTML element of this collection. When parent is set, adding and removing views in the collection synchronizes their elements in the parent element.

    Parameters

    elementOrDocFragment : HTMLElement | DocumentFragment

    Returns

    void
  • inherited

    stopDelegating( [ event ], [ emitter ] ) → void

    Stops delegating events. It can be used at different levels:

    • To stop delegating all events.
    • To stop delegating a specific event to all emitters.
    • To stop delegating a specific event to a specific emitter.

    Parameters

    [ event ] : string

    The name of the event to stop delegating. If omitted, stops it all delegations.

    [ emitter ] : Emitter

    (requires event) The object to stop delegating a particular event to. If omitted, stops delegation of event to all emitters.

    Returns

    void
  • inherited

    stopListening( [ emitter ], [ event ], [ callback ] ) → void

    Stops listening for events. It can be used at different levels:

    • To stop listening to a specific callback.
    • To stop listening to a specific event.
    • To stop listening to all events fired by a specific object.
    • To stop listening to all events fired by all objects.

    Parameters

    [ emitter ] : Emitter

    The object to stop listening to. If omitted, stops it for all objects.

    [ event ] : string

    (Requires the emitter) The name of the event to stop listening to. If omitted, stops it for all events from emitter.

    [ callback ] : Function

    (Requires the event) The function to be removed from the call list for the given event.

    Returns

    void
  • private

    _renderViewIntoCollectionParent( view, [ index ] ) → void

    This method renders a new view added to the collection.

    If the parent element of the collection is set, this method also adds the view's element as a child of the parent in DOM at a specified index.

    Note: If index is not specified, the view's element is pushed as the last child of the parent element.

    Parameters

    view : View<HTMLElement>

    A new view added to the collection.

    [ index ] : number

    An index the view holds in the collection. When not specified, the view is added at the end.

    Returns

    void

Events

  • inherited

    add( eventInfo, item, index )

    Fired when an item is added to the collection.

    Parameters

    eventInfo : EventInfo

    An object containing information about the fired event.

    item : T

    The added item.

    index : number

    An index where the addition occurred.

  • inherited

    change( eventInfo, data )

    Fired when the collection was changed due to adding or removing items.

    Parameters

    eventInfo : EventInfo

    An object containing information about the fired event.

    data : CollectionChangeEventData<T>

    Changed items.

  • inherited

    remove( eventInfo, item, index )

    Fired when an item is removed from the collection.

    Parameters

    eventInfo : EventInfo

    An object containing information about the fired event.

    item : T

    The removed item.

    index : number

    Index from which item was removed.