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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

Properties

  • first

    inherited

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

  • last

    inherited

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

  • length : Number

    inherited

    The number of items available in the collection.

  • locale : Locale

    The editor's locale instance. See the view locale property.

  • _bindToCollection : Collection

    protected inherited

    A collection instance this collection is bound to as a result of calling bindTo method.

  • _bindToExternalToInternalMap : WeakMap

    protected inherited

    A helper mapping external items of a bound collection (bindTo) and actual items of this collection. It provides information necessary to properly remove items bound to another collection.

  • _bindToInternalToExternalMap : WeakMap

    protected inherited

    A helper mapping items of this collection to external items of a bound collection (bindTo). It provides information necessary to manage the bindings, e.g. to avoid loops in two–way bindings.

  • _parentElement : HTMLElement

    protected

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

  • _idProperty : String

    private inherited

    The name of the property which is considered to identify an item.

  • _itemMap : Map

    private inherited

    The internal map of items in the collection.

  • _items : Array.<Object>

    private inherited

    The internal list of items in the collection.

  • _skippedIndexesFromExternal : Array

    private inherited

    Stores indexes of skipped items from bound external collection.

Methods

  • constructor( [ locale ] )

    Creates a new instance of the ViewCollection.

    Parameters

    [ locale ] : Locale

    The editor's locale instance.

  • Symbol.iterator() → Iterable.<*>

    inherited

    Iterable interface.

    Returns

    Iterable.<*>
  • add( item, [ index ] )

    inherited

    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 : Object
    [ index ] : Number

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

    Fires

  • bind( bindProperties ) → Object

    mixed

    Binds observable properties to another objects implementing Observable interface (like Model).

    Once bound, the observable will immediately share the current state of properties of the observable it is bound to and react to the changes to these properties in the future.

    Note: To release the binding use unbind.

    Using bind().to() chain:

    A.bind( 'a' ).to( B );
    A.bind( 'a' ).to( B, 'b' );
    A.bind( 'a', 'b' ).to( B, 'c', 'd' );
    A.bind( 'a' ).to( B, 'b', C, 'd', ( b, d ) => b + d );

    It is also possible to bind to the same property in a observables collection using bind().toMany() chain:

    A.bind( 'a' ).toMany( [ B, C, D ], 'x', ( a, b, c ) => a + b + c );
    A.bind( 'a' ).toMany( [ B, C, D ], 'x', ( ...x ) => x.every( x => x ) );

    Parameters

    bindProperties : String

    Observable properties that will be bound to another observable(s).

    Returns

    Object

    The bind chain with the to() and toMany() methods.

  • bindTo( externalCollection ) → Object

    inherited

    Binds and synchronizes the collection with another one.

    The binding can be a simple factory:

    class FactoryClass {
        constructor( data ) {
            this.label = data.label;
        }
    }
    
    const source = new Collection( { idProperty: 'label' } );
    const target = new Collection();
    
    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 {
        constructor( data ) {
            this.label = data.label;
        }
    }
    
    class BarClass {
        constructor( data ) {
            this.label = data.label;
        }
    }
    
    const source = new Collection( { idProperty: 'label' } );
    const target = new Collection();
    
    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( { idProperty: 'label' } );
    const target = new Collection();
    
    target.bindTo( source ).using( 'label' );
    
    source.add( { label: { value: 'foo' } } );
    source.add( { label: { 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 falsy value:

    const source = new Collection();
    const target = new Collection();
    
    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.

    Parameters

    externalCollection : Collection

    A collection to be bound.

    Returns

    Object
    Collection#bindTo

    return.as

    Collection#bindTo

    return.using

  • clear()

    inherited

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

  • decorate( methodName )

    mixed

    Turns the given methods of this object into event-based ones. This means that the new method will fire an event (named after the method) and the original action will be plugged as a listener to that event.

    This is a very simplified method decoration. Itself it doesn't change the behavior of a method (expect adding the event), but it allows to modify it later on by listening to the method's event.

    For example, in order to cancel the method execution one can stop the event:

    class Foo {
        constructor() {
            this.decorate( 'method' );
        }
    
        method() {
            console.log( 'called!' );
        }
    }
    
    const foo = new Foo();
    foo.on( 'method', ( evt ) => {
        evt.stop();
    }, { priority: 'high' } );
    
    foo.method(); // Nothing is logged.

    Note: we used a high priority listener here to execute this callback before the one which calls the original method (which used the default priority).

    It's also possible to change the return value:

    foo.on( 'method', ( evt ) => {
        evt.return = 'Foo!';
    } );
    
    foo.method(); // -> 'Foo'

    Finally, it's possible to access and modify the parameters:

    method( a, b ) {
        console.log( `${ a }, ${ b }`  );
    }
    
    // ...
    
    foo.on( 'method', ( evt, args ) => {
        args[ 0 ] = 3;
    
        console.log( args[ 1 ] ); // -> 2
    }, { priority: 'high' } );
    
    foo.method( 1, 2 ); // -> '3, 2'

    Parameters

    methodName : String

    Name of the method to decorate.

  • delegate( events ) → EmitterMixinDelegateChain

    mixed

    Delegates selected events to another Emitter. For instance:

    emitterA.delegate( 'eventX' ).to( emitterB );
    emitterA.delegate( 'eventX', 'eventY' ).to( emitterC );

    then eventX is delegated (fired by) emitterB and emitterC along with data:

    emitterA.fire( 'eventX', data );

    and eventY is delegated (fired by) emitterC along with data:

    emitterA.fire( 'eventY', data );

    Parameters

    events : String

    Event names that will be delegated to another emitter.

    Returns

    EmitterMixinDelegateChain
  • destroy()

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

  • filter( callback, callback.item, callback.index ) → Array.<Object>

    inherited

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

    Parameters

    callback : function
    callback.item : Object
    callback.index : Number

    Returns

    Array.<Object>

    The array with matching items.

  • find( callback, callback.item, callback.index ) → Object

    inherited

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

    Parameters

    callback : function
    callback.item : Object
    callback.index : Number

    Returns

    Object

    The item for which callback returned a true value.

  • fire( eventOrInfo, [ args ] ) → *

    mixed

    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.

    Parameters

    eventOrInfo : String | EventInfo

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

    [ args ] : *

    Additional arguments to be passed to the callbacks.

    Returns

    *

    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).

  • get( idOrIndex ) → Object | null

    inherited

    Gets item by its id or index.

    Parameters

    idOrIndex : String | Number

    The item id or index in the collection.

    Returns

    Object | null

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

  • getIndex( idOrItem ) → Number

    inherited

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

    Parameters

    idOrItem : String | Object

    The item or its id in the collection.

    Returns

    Number

    Index of given item.

  • listenTo( emitter, event, callback, [ options ] = { [options.priority] } )

    mixed

    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.

    Parameters

    emitter : Emitter

    The object that fires the event.

    event : String

    The name of the event.

    callback : function

    The function to be called on event.

    [ options ] : Object

    Additional options.

    Properties
    [ options.priority ] : PriorityString | Number

    The priority of this event callback. The higher the priority value the sooner the callback will be fired. Events having the same priority are called in the order they were added.

    Defaults to 'normal'

    Defaults to {}

  • map( callback, callback.item, callback.index ) → Array

    inherited

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

    Parameters

    callback : function
    callback.item : Object
    callback.index : Number

    Returns

    Array

    The result of mapping.

  • off( event, callback )

    mixed

    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.

  • on( event, callback, [ options ] = { [options.priority] } )

    mixed

    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).

    Parameters

    event : String

    The name of the event.

    callback : function

    The function to be called on event.

    [ options ] : Object

    Additional options.

    Properties
    [ options.priority ] : PriorityString | Number

    The priority of this event callback. The higher the priority value the sooner the callback will be fired. Events having the same priority are called in the order they were added.

    Defaults to 'normal'

    Defaults to {}

  • once( event, callback, [ options ] = { [options.priority] } )

    mixed

    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.

    Parameters

    event : String

    The name of the event.

    callback : function

    The function to be called on event.

    [ options ] : Object

    Additional options.

    Properties
    [ options.priority ] : PriorityString | Number

    The priority of this event callback. The higher the priority value the sooner the callback will be fired. Events having the same priority are called in the order they were added.

    Defaults to 'normal'

    Defaults to {}

  • remove( subject ) → Object

    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 : View | Number | String

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

    Returns

    Object

    The removed view.

    Overrides: Collection#remove
  • set( name, [ value ] )

    mixed

    Creates and sets the value of an observable property of this object. Such an property becomes a part of the state and is be observable.

    It accepts also a single object literal containing key/value pairs with properties to be set.

    This method throws the observable-set-cannot-override error if the observable instance already have a property with the given property name. This prevents from mistakenly overriding existing properties and methods, but means that foo.set( 'bar', 1 ) may be slightly slower than foo.bar = 1.

    Parameters

    name : String | Object

    The property's name or object with name=>value pairs.

    [ value ] : *

    The property's value (if name was passed in the first parameter).

  • setParent( element )

    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

    element : HTMLElement

    A new parent element.

  • stopDelegating( [ event ], [ emitter ] )

    mixed

    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.

  • stopListening( [ emitter ], [ event ], [ callback ] )

    mixed

    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.

  • unbind( [ unbindProperties ] )

    mixed

    Removes the binding created with bind.

    A.unbind( 'a' );
    A.unbind();

    Parameters

    [ unbindProperties ] : String

    Observable properties to be unbound. All the bindings will be released if no properties provided.

  • _setUpBindToBinding( factory )

    protected inherited

    Finalizes and activates a binding initiated by {#bindTo}.

    Parameters

    factory : function

    A function which produces collection items.

Events

  • add( eventInfo, item )

    inherited

    Fired when an item is added to the collection.

    Parameters

    eventInfo : EventInfo

    An object containing information about the fired event.

    item : Object

    The added item.

  • change:{property}( eventInfo, name, value, oldValue )

    mixed

    Fired when a property changed value.

    observable.set( 'prop', 1 );
    
    observable.on( 'change:prop', ( evt, propertyName, newValue, oldValue ) => {
        console.log( `${ propertyName } has changed from ${ oldValue } to ${ newValue }` );
    } );
    
    observable.prop = 2; // -> 'prop has changed from 1 to 2'

    Parameters

    eventInfo : EventInfo

    An object containing information about the fired event.

    name : String

    The property name.

    value : *

    The new property value.

    oldValue : *

    The previous property value.

  • remove( eventInfo, item, index )

    inherited

    Fired when an item is removed from the collection.

    Parameters

    eventInfo : EventInfo

    An object containing information about the fired event.

    item : Object

    The removed item.

    index : Number

    Index from which item was removed.

  • set:{property}( eventInfo, name, value, oldValue )

    mixed

    Fired when a property value is going to be set but is not set yet (before the change event is fired).

    You can control the final value of the property by using the event's return property.

    observable.set( 'prop', 1 );
    
    observable.on( 'set:prop', ( evt, propertyName, newValue, oldValue ) => {
        console.log( `Value is going to be changed from ${ oldValue } to ${ newValue }` );
        console.log( `Current property value is ${ observable[ propertyName ] }` );
    
        // Let's override the value.
        evt.return = 3;
    } );
    
    observable.on( 'change:prop', ( evt, propertyName, newValue, oldValue ) => {
        console.log( `Value has changed from ${ oldValue } to ${ newValue }` );
    } );
    
    observable.prop = 2; // -> 'Value is going to be changed from 1 to 2'
                         // -> 'Current property value is 1'
                         // -> 'Value has changed from 1 to 3'

    Note: Event is fired even when the new value is the same as the old value.

    Parameters

    eventInfo : EventInfo

    An object containing information about the fired event.

    name : String

    The property name.

    value : *

    The new property value.

    oldValue : *

    The previous property value.