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

Public
Inherited
Mixed
Protected
Private
Deprecated

Properties

first

inherited

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

See source
last

inherited

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

See source
length : Number

inherited

The number of items available in the collection.

See source
locale : Locale

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

See source
_bindToCollection : Collection

protected inherited

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

See source
_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.

See source

See _bindToInternalToExternalMap.
_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.

See source

See _bindToExternalToInternalMap.
_parentElement : HTMLElement

protected

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

See source
_idProperty : String

private inherited

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

See source
_itemMap : Map

private inherited

The internal map of items in the collection.

See source
_items : Array.<Object>

private inherited

The internal list of items in the collection.

See source
_skippedIndexesFromExternal : Array

private inherited

Stores indexes of skipped items from bound external collection.

See source

Methods

constructor( [ locale ] )

Creates a new instance of the ViewCollection.

See source

Parameters

[ locale ] : Locale

The editor's locale instance.
Symbol.iterator() → Iterable.<*>

inherited

Iterable interface.

See source

Returns

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

inherited
Adds an item into the collection.

See source
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
- add
bind( bindProperties ) → Object
Binds obvervable properties to other objects implementing the Observable interface.

See source
Read more in the dedicated guide covering the topic of property bindings with some additional examples.

Let's consider two objects: a button and an associated command (both Observable).

A simple property binding could be as follows:
```
button.bind( 'isEnabled' ).to( command, 'isEnabled' );
```
or even shorter:
```
button.bind( 'isEnabled' ).to( command );
```
which works in the following way:
- button.isEnabled instantly equals command.isEnabled,
- whenever command.isEnabled changes, button.isEnabled will immediately reflect its value.
Note: To release the binding use unbind.

You can also "rename" the property in the binding by specifying the new name in the to() chain:
```
button.bind( 'isEnabled' ).to( command, 'isWorking' );
```
It is possible to bind more than one property at a time to shorten the code:
```
button.bind( 'isEnabled', 'value' ).to( command );
```
which corresponds to:
```
button.bind( 'isEnabled' ).to( command );
button.bind( 'value' ).to( command );
```
The binding can include more than one observable, combining multiple data sources in a custom callback:
```
button.bind( 'isEnabled' ).to( command, 'isEnabled', ui, 'isVisible',
    ( isCommandEnabled, isUIVisible ) => isCommandEnabled && isUIVisible );
```
It is also possible to bind to the same property in an array of observables. To bind a button to multiple commands (also Observables) so that each and every one of them must be enabled for the button to become enabled, use the following code:
```
button.bind( 'isEnabled' ).toMany( [ commandA, commandB, commandC ], 'isEnabled',
    ( isAEnabled, isBEnabled, isCEnabled ) => isAEnabled && isBEnabled && isCEnabled );
```
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.

See source

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.

See source
decorate( methodName )
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.

See source
Read more in the dedicated guide covering the topic of decorating methods with some additional examples.

Decorating the method does not change its behavior (it only adds an event), but it allows to modify it later on by listening to the method's event.

For example, to cancel the method execution the event can be stopped:
```
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: The high priority listener has been used to execute this particular callback before the one which calls the original method (which uses the "normal" priority).

It is also possible to change the returned value:
```
foo.on( 'method', ( evt ) => {
    evt.return = 'Foo!';
} );

foo.method(); // -> 'Foo'
```
Finally, it is possible to access and modify the arguments the method is called with:
```
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

inherited
Delegates selected events to another Emitter. For instance:

See source
```
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.

See source
filter( callback, callback.item, callback.index, ctx ) → Array.<Object>

inherited

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

See source

Parameters

callback : function

callback.item : Object

callback.index : Number

ctx : Object

Context in which the callback will be called.

Returns

Array.<Object>

The array with matching items.
find( callback, callback.item, callback.index, ctx ) → Object

inherited

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

See source

Parameters

callback : function

callback.item : Object

callback.index : Number

ctx : Object

Context in which the callback will be called.

Returns

Object

The item for which callback returned a true value.
fire( eventOrInfo, [ args ] ) → *

inherited

Fires an event, executing all callbacks registered for it.

See source

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.

See source

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.

See source

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] } )

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

See source
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, ctx ) → Array

inherited

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

See source

Parameters

callback : function

callback.item : Object

callback.index : Number

ctx : Object

Context in which the callback will be called.

Returns

Array

The result of mapping.
off( event, callback )

inherited

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

See source

Parameters

event : String

The name of the event.

callback : function

The function to stop being called.
on( event, callback, [ options ] = { [options.priority] } )

inherited

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

See source

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] } )

inherited

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.

See source

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 source

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.
set( name, [ value ] )

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.

See source

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.

See source

Parameters

element : HTMLElement

A new parent element.
stopDelegating( [ event ], [ emitter ] )

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

See source
- 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 ] )

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

See source
- 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 ] )
Removes the binding created with bind.

See source
```
// Removes the binding for the 'a' property.
A.unbind( 'a' );

// Removes bindings for all properties.
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}.

See source

Parameters

factory : function

A function which produces collection items.

Events

add( eventInfo, item )

inherited

Fired when an item is added to the collection.

See source

Parameters

eventInfo : EventInfo

An object containing information about the fired event.

item : Object

The added item.
change:{property}( eventInfo, name, value, oldValue )
Fired when a property changed value.

See source
```
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.

See source

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

See source
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.

ViewCollection (ui)

Filtering

Properties

firstmodule:ui/viewcollection~ViewCollection#first

lastmodule:ui/viewcollection~ViewCollection#last

length : Numbermodule:ui/viewcollection~ViewCollection#length

locale : Localemodule:ui/viewcollection~ViewCollection#locale

_bindToCollection : Collectionmodule:ui/viewcollection~ViewCollection#_bindToCollection

_bindToExternalToInternalMap : WeakMapmodule:ui/viewcollection~ViewCollection#_bindToExternalToInternalMap

_bindToInternalToExternalMap : WeakMapmodule:ui/viewcollection~ViewCollection#_bindToInternalToExternalMap

_parentElement : HTMLElementmodule:ui/viewcollection~ViewCollection#_parentElement

_idProperty : Stringmodule:ui/viewcollection~ViewCollection#_idProperty

_itemMap : Mapmodule:ui/viewcollection~ViewCollection#_itemMap

_items : Array.<Object>module:ui/viewcollection~ViewCollection#_items

_skippedIndexesFromExternal : Arraymodule:ui/viewcollection~ViewCollection#_skippedIndexesFromExternal

Methods

constructor( [ locale ] )module:ui/viewcollection~ViewCollection#constructor

Parameters

Symbol.iterator() → Iterable.<*>module:ui/viewcollection~ViewCollection#Symbol.iterator

Returns

add( item, [ index ] )module:ui/viewcollection~ViewCollection#add

Parameters

Fires

bind( bindProperties ) → Objectmodule:ui/viewcollection~ViewCollection#bind

Parameters

Returns

bindTo( externalCollection ) → Objectmodule:ui/viewcollection~ViewCollection#bindTo

Parameters

Returns

clear()module:ui/viewcollection~ViewCollection#clear

decorate( methodName )module:ui/viewcollection~ViewCollection#decorate

Parameters

delegate( events ) → EmitterMixinDelegateChainmodule:ui/viewcollection~ViewCollection#delegate

Parameters

Returns

destroy()module:ui/viewcollection~ViewCollection#destroy

filter( callback, callback.item, callback.index, ctx ) → Array.<Object>module:ui/viewcollection~ViewCollection#filter

Parameters

Returns

find( callback, callback.item, callback.index, ctx ) → Objectmodule:ui/viewcollection~ViewCollection#find

Parameters

Returns

fire( eventOrInfo, [ args ] ) → *module:ui/viewcollection~ViewCollection#fire

Parameters

Returns

get( idOrIndex ) → Object | nullmodule:ui/viewcollection~ViewCollection#get

Parameters

Returns

getIndex( idOrItem ) → Numbermodule:ui/viewcollection~ViewCollection#getIndex

Parameters

Returns

listenTo( emitter, event, callback, [ options ] = { [options.priority] } )module:ui/viewcollection~ViewCollection#listenTo

Parameters

map( callback, callback.item, callback.index, ctx ) → Arraymodule:ui/viewcollection~ViewCollection#map

Parameters

Returns

off( event, callback )module:ui/viewcollection~ViewCollection#off

Parameters

on( event, callback, [ options ] = { [options.priority] } )module:ui/viewcollection~ViewCollection#on

Parameters

once( event, callback, [ options ] = { [options.priority] } )module:ui/viewcollection~ViewCollection#once

Parameters

remove( subject ) → Objectmodule:ui/viewcollection~ViewCollection#remove

Parameters

Returns

set( name, [ value ] )module:ui/viewcollection~ViewCollection#set

Parameters

setParent( element )module:ui/viewcollection~ViewCollection#setParent

Parameters

stopDelegating( [ event ], [ emitter ] )module:ui/viewcollection~ViewCollection#stopDelegating

Parameters

stopListening( [ emitter ], [ event ], [ callback ] )module:ui/viewcollection~ViewCollection#stopListening

Parameters

unbind( [ unbindProperties ] )module:ui/viewcollection~ViewCollection#unbind

Parameters

_setUpBindToBinding( factory )module:ui/viewcollection~ViewCollection#_setUpBindToBinding

Parameters

Events

add( eventInfo, item )module:ui/viewcollection~ViewCollection#event:add

Parameters

`first`

`last`

`length : Number`

`locale : Locale`

`_bindToCollection : Collection`

`_bindToExternalToInternalMap : WeakMap`

`_bindToInternalToExternalMap : WeakMap`

`_parentElement : HTMLElement`

`_idProperty : String`

`_itemMap : Map`

`_items : Array.<Object>`

`_skippedIndexesFromExternal : Array`

`constructor( [ locale ] )`

`Symbol.iterator() → Iterable.<*>`

`add( item, [ index ] )`

`bind( bindProperties ) → Object`

`bindTo( externalCollection ) → Object`

`clear()`

`decorate( methodName )`

`delegate( events ) → EmitterMixinDelegateChain`

`destroy()`

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

`find( callback, callback.item, callback.index, ctx ) → Object`

`fire( eventOrInfo, [ args ] ) → *`

`get( idOrIndex ) → Object | null`

`getIndex( idOrItem ) → Number`

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

`map( callback, callback.item, callback.index, ctx ) → Array`

`off( event, callback )`

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

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

`remove( subject ) → Object`

`set( name, [ value ] )`

`setParent( element )`

`stopDelegating( [ event ], [ emitter ] )`

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

`unbind( [ unbindProperties ] )`

`_setUpBindToBinding( factory )`

`add( eventInfo, item )`

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

`remove( eventInfo, item, index )`

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