ModelSchema

A dictionary containing attribute properties.

Stores additional callbacks registered for attribute names, which are evaluated when checkAttribute is called.

Keys are schema attribute names for which the callbacks are registered. Values are arrays with the callbacks.

Some checks are added under _genericCheckSymbol key, these are evaluated for every checkAttribute call.

Stores additional callbacks registered for schema items, which are evaluated when checkChild is called.

Keys are schema item names for which the callbacks are registered. Values are arrays with the callbacks.

Some checks are added under _genericCheckSymbol key, these are evaluated for every checkChild call.

Creates a schema instance.

Allows registering a callback to the checkAttribute method calls.

Callbacks allow you to implement rules which are not otherwise possible to achieve by using the declarative API of ModelSchemaItemDefinition.

Note that callback checks have bigger priority than declarative rules checks and may overwrite them.

For example, by using this method you can disallow setting attributes on nodes in specific contexts:

// Disallow setting `bold` on text inside `heading1` element:
schema.addAttributeCheck( context => {
	if ( context.endsWith( 'heading1 $text' ) ) {
		return false;
	}
}, 'bold' );

You can skip the optional attributeName parameter to evaluate the callback for every checkAttribute() call.

// Disallow formatting attributes on text inside custom `myTitle` element:
schema.addAttributeCheck( ( context, attributeName ) => {
	if ( context.endsWith( 'myTitle $text' ) && schema.getAttributeProperties( attributeName ).isFormatting ) {
		return false;
	}
} );

Please note that the generic callbacks may affect the editor performance and should be avoided if possible.

When one of the callbacks makes a decision (returns true or false) the processing is finished and other callbacks are not fired. Callbacks are fired in the order they were added, however generic callbacks are fired before callbacks added for a specified item.

You can also use event-checkAttribute event, if you need even better control. The result from the example above could also be achieved with following event callback:

schema.on( 'checkAttribute', ( evt, args ) => {
	const context = args[ 0 ];
	const attributeName = args[ 1 ];

	if ( context.endsWith( 'myTitle $text' ) && schema.getAttributeProperties( attributeName ).isFormatting ) {
		// Prevent next listeners from being called.
		evt.stop();
		// Set the `checkAttribute()` return value.
		evt.return = false;
	}
}, { priority: 'high' } );

Note that the callback checks and declarative rules checks are processed on normal priority.

Adding callbacks this way can also negatively impact editor performance.

Parameters

callback : ModelSchemaAttributeCheckCallback

The callback to be called. It is called with two parameters: context and attribute name. The callback may return true or false, to override checkAttribute()'s return value. If it does not return a boolean value, the default algorithm (or other callbacks) will define checkAttribute()'s return value.

[ attributeName ] : string

Name of the attribute for which the callback is registered. If specified, the callback will be run only for checkAttribute() calls with matching attributeName. Otherwise, the callback will run for every checkAttribute() call.

Returns

void

Allows registering a callback to the checkChild method calls.

Callbacks allow you to implement rules which are not otherwise possible to achieve by using the declarative API of ModelSchemaItemDefinition.

Note that callback checks have bigger priority than declarative rules checks and may overwrite them.

For example, by using this method you can disallow elements in specific contexts:

// Disallow `heading1` inside a `blockQuote` that is inside a table.
schema.addChildCheck( ( context, childDefinition ) => {
	if ( context.endsWith( 'tableCell blockQuote' ) ) {
		return false;
	}
}, 'heading1' );

You can skip the optional itemName parameter to evaluate the callback for every checkChild() call.

// Inside specific custom element, allow only children, which allows for a specific attribute.
schema.addChildCheck( ( context, childDefinition ) => {
	if ( context.endsWith( 'myElement' ) ) {
		return childDefinition.allowAttributes.includes( 'myAttribute' );
	}
} );

Please note that the generic callbacks may affect the editor performance and should be avoided if possible.

When one of the callbacks makes a decision (returns true or false) the processing is finished and other callbacks are not fired. Callbacks are fired in the order they were added, however generic callbacks are fired before callbacks added for a specified item.

You can also use checkChild event, if you need even better control. The result from the example above could also be achieved with following event callback:

schema.on( 'checkChild', ( evt, args ) => {
	const context = args[ 0 ];
	const childDefinition = args[ 1 ];

	if ( context.endsWith( 'myElement' ) ) {
		// Prevent next listeners from being called.
		evt.stop();
		// Set the `checkChild()` return value.
		evt.return = childDefinition.allowAttributes.includes( 'myAttribute' );
	}
}, { priority: 'high' } );

Note that the callback checks and declarative rules checks are processed on normal priority.

Adding callbacks this way can also negatively impact editor performance.

Parameters

callback : ModelSchemaChildCheckCallback

The callback to be called. It is called with two parameters: ModelSchemaContext (context) instance and ModelSchemaCompiledItemDefinition (definition). The callback may return true/false to override checkChild()'s return value. If it does not return a boolean value, the default algorithm (or other callbacks) will define checkChild()'s return value.

[ itemName ] : string

Name of the schema item for which the callback is registered. If specified, the callback will be run only for checkChild() calls which def parameter matches the itemName. Otherwise, the callback will run for every checkChild call.

Returns

void

Binds observable properties to other objects implementing the Observable interface.

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

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 );

Using a custom callback allows processing the value before passing it to the target property:

button.bind( 'isEnabled' ).to( command, 'value', value => value === 'heading1' );

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 );

Type parameters

K1

K2

Parameters

bindProperty1 : K1

Observable property that will be bound to other observable(s).

bindProperty2 : K2

Observable property that will be bound to other observable(s).

Returns

ObservableDualBindChain<K1, ModelSchema[ K1 ], K2, ModelSchema[ K2 ]>

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

Binds observable properties to other objects implementing the Observable interface.

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

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 );

Using a custom callback allows processing the value before passing it to the target property:

button.bind( 'isEnabled' ).to( command, 'value', value => value === 'heading1' );

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 : Array<'off' | 'set' | 'bind' | 'unbind' | 'decorate' | 'stopListening' | 'on' | 'once' | 'listenTo' | 'fire' | 'delegate' | 'stopDelegating' | 'register' | 'extend' | 'getDefinitions' | 'getDefinition' | 'isRegistered' | 'isBlock' | 'isLimit' | 'isObject' | 'isInline' | 'isSelectable' | 'isContent' | 'checkChild' | 'checkAttribute' | 'checkMerge' | 'addChildCheck' | 'addAttributeCheck' | 'setAttributeProperties' | 'getAttributeProperties' | 'getLimitElement' | 'checkAttributeInSelection' | 'getValidRanges' | 'getNearestSelectionRange' | 'findAllowedParent' | 'setAllowedAttributes' | 'removeDisallowedAttributes' | 'getAttributesWithProperty' | 'createContext' | 'findOptimalInsertionRange'>

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

Returns

ObservableMultiBindChain

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

Binds observable properties to other objects implementing the Observable interface.

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

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 );

Using a custom callback allows processing the value before passing it to the target property:

button.bind( 'isEnabled' ).to( command, 'value', value => value === 'heading1' );

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 );

Type parameters

K

Parameters

bindProperty : K

Observable property that will be bound to other observable(s).

Returns

ObservableSingleBindChain<K, ModelSchema[ K ]>

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

Checks whether the given attribute can be applied in the given context (on the last item of the context).

schema.checkAttribute( textNode, 'bold' ); // -> false

schema.extend( '$text', {
	allowAttributes: 'bold'
} );

schema.checkAttribute( textNode, 'bold' ); // -> true

Both callback checks and declarative rules (added when registering and extending items) are evaluated when this method is called.

Note that callback checks have bigger priority than declarative rules checks and may overwrite them.

Parameters

context : ModelSchemaContextDefinition

The context in which the attribute will be checked.

attributeName : string

Name of attribute to check in the given context.

Returns

boolean

Fires

• checkAttribute

Checks whether the attribute is allowed in selection:

• if the selection is not collapsed, then checks if the attribute is allowed on any of nodes in that range,
• if the selection is collapsed, then checks if on the selection position there's a text with the specified attribute allowed.

Parameters

selection : ModelSelection | ModelDocumentSelection

Selection which will be checked.

attribute : string

The name of the attribute to check.

Returns

boolean

Checks whether the given node can be a child of the given context.

schema.checkChild( model.document.getRoot(), paragraph ); // -> false

schema.register( 'paragraph', {
	allowIn: '$root'
} );

schema.checkChild( model.document.getRoot(), paragraph ); // -> true

Both callback checks and declarative rules (added when registering and extending items) are evaluated when this method is called.

Note that callback checks have bigger priority than declarative rules checks and may overwrite them.

Note that when verifying whether the given node can be a child of the given context, the schema also verifies the entire context – from its root to its last element. Therefore, it is possible for checkChild() to return false even though the context last element can contain the checked child. It happens if one of the context elements does not allow its child. When context is verified, custom checks are considered as well.

Parameters

context : ModelSchemaContextDefinition

The context in which the child will be checked.

def : string | ModelNode | ModelDocumentFragment

The child to check.

Returns

boolean

Fires

• checkChild

Parameters

baseElement : ModelElement

elementToMerge : ModelElement

Returns

boolean

Parameters

position : ModelPosition

Returns

boolean

Creates an instance of the schema context.

Parameters

context : ModelSchemaContextDefinition

Returns

ModelSchemaContext

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.

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 extends ObservableMixin() {
	constructor() {
		super();
		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 : 'off' | 'set' | 'bind' | 'unbind' | 'decorate' | 'stopListening' | 'on' | 'once' | 'listenTo' | 'fire' | 'delegate' | 'stopDelegating' | 'register' | 'extend' | 'getDefinitions' | 'getDefinition' | 'isRegistered' | 'isBlock' | 'isLimit' | 'isObject' | 'isInline' | 'isSelectable' | 'isContent' | 'checkChild' | 'checkAttribute' | 'checkMerge' | 'addChildCheck' | 'addAttributeCheck' | 'setAttributeProperties' | 'getAttributeProperties' | 'getLimitElement' | 'checkAttributeInSelection' | 'getValidRanges' | 'getNearestSelectionRange' | 'findAllowedParent' | 'setAllowedAttributes' | 'removeDisallowedAttributes' | 'getAttributesWithProperty' | 'createContext' | 'findOptimalInsertionRange'

Name of the method to decorate.

Returns

void

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 : Array<string>

Event names that will be delegated to another emitter.

Returns

EmitterMixinDelegateChain

Extends a registered item's definition.

Extending properties such as allowIn will add more items to the existing properties, while redefining properties such as isBlock will override the previously defined ones.

schema.register( 'foo', {
	allowIn: '$root',
	isBlock: true;
} );
schema.extend( 'foo', {
	allowIn: 'blockQuote',
	isBlock: false
} );

schema.getDefinition( 'foo' );
//	{
//		allowIn: [ '$root', 'blockQuote' ],
// 		isBlock: false
//	}

Parameters

itemName : string

definition : ModelSchemaItemDefinition

Returns

void

Tries to find position ancestors that allow to insert a given node. It starts searching from the given position and goes node by node to the top of the model tree as long as a limit element, an object element or a topmost ancestor is not reached.

Parameters

position : ModelPosition

The position that the search will start from.

node : string | ModelNode

The node for which an allowed parent should be found or its name.

Returns

null | ModelElement

Allowed parent or null if nothing was found.

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).

Returns properties associated with a given model attribute. See setAttributeProperties().

Parameters

attributeName : string

A name of the attribute.

Returns

ModelAttributeProperties

Gets attributes of a node that have a given property.

Parameters

node : ModelNode

Node to get attributes from.

propertyName : string

Name of the property that attribute must have to return it.

propertyValue : unknown

Desired value of the property that we want to check. When undefined attributes will be returned if they have set a given property no matter what the value is. If specified it will return attributes which given property's value is equal to this parameter.

Returns

Record<string, unknown>

Object with attributes' names as key and attributes' values as value.

Returns a definition of the given item or undefined if an item is not registered.

This method should normally be used for reflection purposes (e.g. defining a clone of a certain element, checking a list of all block elements, etc). Use specific methods (such as checkChild() or isLimit()) in other cases.

Parameters

item : string | ModelDocumentFragment | ModelItem | ModelSchemaContextItem

Returns

undefined | ModelSchemaCompiledItemDefinition

Returns data of all registered items.

This method should normally be used for reflection purposes (e.g. defining a clone of a certain element, checking a list of all block elements, etc). Use specific methods (such as checkChild() or isLimit()) in other cases.

Returns

Record<string, ModelSchemaCompiledItemDefinition>

Returns the lowest limit element containing the entire selection/range/position or the root otherwise.

Parameters

selectionOrRangeOrPosition : ModelPosition | ModelRange | ModelSelection | ModelDocumentSelection

The selection/range/position to check.

Returns

ModelElement

The lowest limit element containing the entire selectionOrRangeOrPosition.

Basing on given position, finds and returns a range which is nearest to that position and is a correct range for selection.

The correct selection range might be collapsed when it is located in a position where the text node can be placed. Non-collapsed range is returned when selection can be placed around element marked as an "object" in the schema.

Direction of searching for the nearest correct selection range can be specified as:

• both - searching will be performed in both ways,
• forward - searching will be performed only forward,
• backward - searching will be performed only backward.

When valid selection range cannot be found, null is returned.

Parameters

position : ModelPosition

Reference position where new selection range should be looked for.

direction : 'forward' | 'backward' | 'both'

Search direction.

Defaults to 'both'

Returns

null | ModelRange

Nearest selection range or null if one cannot be found.

Transforms the given set of ranges into a set of ranges where the given attribute is allowed (and can be applied).

Parameters

ranges : Iterable<ModelRange>

Ranges to be validated.

attribute : string

The name of the attribute to check.

Returns

IterableIterator<ModelRange>

Ranges in which the attribute is allowed.

Returns true if the given item is defined to be a block by the ModelSchemaItemDefinition's isBlock property.

schema.isBlock( 'paragraph' ); // -> true
schema.isBlock( '$root' ); // -> false

const paragraphElement = writer.createElement( 'paragraph' );
schema.isBlock( paragraphElement ); // -> true

See the Block elements section of the Schema deep-dive guide for more details.

Parameters

item : string | ModelDocumentFragment | ModelItem | ModelSchemaContextItem

Returns

boolean

Returns true if the given item is defined to be a content by the ModelSchemaItemDefinition's isContent property.

schema.isContent( 'paragraph' ); // -> false
schema.isContent( 'heading1' ); // -> false
schema.isContent( 'imageBlock' ); // -> true
schema.isContent( 'horizontalLine' ); // -> true

const text = writer.createText( 'foo' );
schema.isContent( text ); // -> true

See the Content elements section of the Schema deep-dive guide for more details.

Parameters

item : string | ModelDocumentFragment | ModelItem | ModelSchemaContextItem

Returns

boolean

Returns true if the given item is defined to be an inline element by the ModelSchemaItemDefinition's isInline property.

schema.isInline( 'paragraph' ); // -> false
schema.isInline( 'softBreak' ); // -> true

const text = writer.createText( 'foo' );
schema.isInline( text ); // -> true

See the Inline elements section of the Schema deep-dive guide for more details.

Parameters

item : string | ModelDocumentFragment | ModelItem | ModelSchemaContextItem

Returns

boolean

Returns true if the given item should be treated as a limit element.

It considers an item to be a limit element if its ModelSchemaItemDefinition's isLimit or isObject property was set to true.

schema.isLimit( 'paragraph' ); // -> false
schema.isLimit( '$root' ); // -> true
schema.isLimit( editor.model.document.getRoot() ); // -> true
schema.isLimit( 'imageBlock' ); // -> true

See the Limit elements section of the Schema deep-dive guide for more details.

Parameters

item : string | ModelDocumentFragment | ModelItem | ModelSchemaContextItem

Returns

boolean

Returns true if the given item should be treated as an object element.

It considers an item to be an object element if its ModelSchemaItemDefinition's isObject property was set to true.

schema.isObject( 'paragraph' ); // -> false
schema.isObject( 'imageBlock' ); // -> true

const imageElement = writer.createElement( 'imageBlock' );
schema.isObject( imageElement ); // -> true

See the Object elements section of the Schema deep-dive guide for more details.

Parameters

item : string | ModelDocumentFragment | ModelItem | ModelSchemaContextItem

Returns

boolean

Returns true if the given item is registered in the schema.

schema.isRegistered( 'paragraph' ); // -> true
schema.isRegistered( editor.model.document.getRoot() ); // -> true
schema.isRegistered( 'foo' ); // -> false

Parameters

item : string | ModelDocumentFragment | ModelItem | ModelSchemaContextItem

Returns

boolean

Returns true if the given item is defined to be a selectable element by the ModelSchemaItemDefinition's isSelectable property.

schema.isSelectable( 'paragraph' ); // -> false
schema.isSelectable( 'heading1' ); // -> false
schema.isSelectable( 'imageBlock' ); // -> true
schema.isSelectable( 'tableCell' ); // -> true

const text = writer.createText( 'foo' );
schema.isSelectable( text ); // -> false

See the Selectable elements section of the Schema deep-dive guide for more details.

Parameters

item : string | ModelDocumentFragment | ModelItem | ModelSchemaContextItem

Returns

boolean

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

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

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

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

Registers a schema item. Can only be called once for every item name.

schema.register( 'paragraph', {
	inheritAllFrom: '$block'
} );

Parameters

itemName : string

[ definition ] : ModelSchemaItemDefinition

Returns

void

Removes attributes disallowed by the schema.

Parameters

nodes : Iterable<ModelNode>

Nodes that will be filtered.

writer : ModelWriter

Returns

void

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

It accepts 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 has 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.

In TypeScript, those properties should be declared in class using declare keyword. In example:

public declare myProp1: number;
public declare myProp2: string;

constructor() {
	this.set( {
		'myProp1: 2,
		'myProp2: 'foo'
	} );
}

Parameters

values : object

An object with name=>value pairs.

Returns

void

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

This method throws the observable-set-cannot-override error if the observable instance already has 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.

In TypeScript, those properties should be declared in class using declare keyword. In example:

public declare myProp: number;

constructor() {
	this.set( 'myProp', 2 );
}

Type parameters

K

Parameters

name : K

The property's name.

value : ModelSchema[ K ]

The property's value.

Returns

void

Sets attributes allowed by the schema on a given node.

Parameters

node : ModelNode

A node to set attributes on.

attributes : Record<string, unknown>

Attributes keys and values.

writer : ModelWriter

An instance of the model writer.

Returns

void

This method allows assigning additional metadata to the model attributes. For example, AttributeProperties#isFormatting property is used to mark formatting attributes (like bold or italic).

// Mark bold as a formatting attribute.
schema.setAttributeProperties( 'bold', {
	isFormatting: true
} );

// Override code not to be considered a formatting markup.
schema.setAttributeProperties( 'code', {
	isFormatting: false
} );

Properties are not limited to members defined in the AttributeProperties type and you can also use custom properties:

schema.setAttributeProperties( 'blockQuote', {
	customProperty: 'value'
} );

Subsequent calls with the same attribute will extend its custom properties:

schema.setAttributeProperties( 'blockQuote', {
	one: 1
} );

schema.setAttributeProperties( 'blockQuote', {
	two: 2
} );

console.log( schema.getAttributeProperties( 'blockQuote' ) );
// Logs: { one: 1, two: 2 }

Parameters

attributeName : string

A name of the attribute to receive the properties.

properties : ModelAttributeProperties

A dictionary of properties.

Returns

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

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

Removes the binding created with bind.

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

// Removes bindings for all properties.
A.unbind();

Parameters

unbindProperties : Array<'off' | 'set' | 'bind' | 'unbind' | 'decorate' | 'stopListening' | 'on' | 'once' | 'listenTo' | 'fire' | 'delegate' | 'stopDelegating' | 'register' | 'extend' | 'getDefinitions' | 'getDefinition' | 'isRegistered' | 'isBlock' | 'isLimit' | 'isObject' | 'isInline' | 'isSelectable' | 'isContent' | 'checkChild' | 'checkAttribute' | 'checkMerge' | 'addChildCheck' | 'addAttributeCheck' | 'setAttributeProperties' | 'getAttributeProperties' | 'getLimitElement' | 'checkAttributeInSelection' | 'getValidRanges' | 'getNearestSelectionRange' | 'findAllowedParent' | 'setAllowedAttributes' | 'removeDisallowedAttributes' | 'getAttributesWithProperty' | 'createContext' | 'findOptimalInsertionRange'>

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

Returns

void

Returns a model range which is optimal (in terms of UX) for inserting a widget block.

For instance, if a selection is in the middle of a paragraph, the collapsed range before this paragraph will be returned so that it is not split. If the selection is at the end of a paragraph, the collapsed range after this paragraph will be returned.

Note: If the selection is placed in an empty block, the range in that block will be returned. If that range is then passed to insertContent, the block will be fully replaced by the inserted widget block.

Parameters

selection : ModelSelection | ModelDocumentSelection

The selection based on which the insertion position should be calculated.

[ place ] : 'auto' | 'after' | 'before'

The place where to look for optimal insertion range. The auto value will determine itself the best position for insertion. The before value will try to find a position before selection. The after value will try to find a position after selection.

Returns

ModelRange

The optimal range.

Parameters

context : ModelSchemaContext

def : ModelSchemaCompiledItemDefinition

Returns

boolean

Returns

void

Returns

void

Calls attribute check callbacks to decide whether attributeName can be set on the last element of context. It uses both generic and specific (defined for attributeName) callbacks. If neither callback makes a decision, undefined is returned.

Note that the first callback that makes a decision "wins", i.e., if any callback returns true or false, then the processing is over and that result is returned.

Parameters

context : ModelSchemaContext

attributeName : string

Returns

undefined | boolean

Calls child check callbacks to decide whether def is allowed in context. It uses both generic and specific (defined for def item) callbacks. If neither callback makes a decision, undefined is returned.

Note that the first callback that makes a decision "wins", i.e., if any callback returns true or false, then the processing is over and that result is returned.

Parameters

context : ModelSchemaContext

def : ModelSchemaCompiledItemDefinition

Returns

undefined | boolean

Takes a flat range and an attribute name. Traverses the range recursively and deeply to find and return all ranges inside the given range on which the attribute can be applied.

This is a helper function for getValidRanges.

Parameters

range : ModelRange

The range to process.

attribute : string

The name of the attribute to check.

Returns

Iterable<ModelRange>

Ranges in which the attribute is allowed.

Fired when a property changed value.

observable.set( 'prop', 1 );

observable.on<ObservableChangeEvent<number>>( '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 : TValue

The new property value.

oldValue : TValue

The previous property value.

Event fired when the checkAttribute method is called. It allows plugging in additional behavior, for example implementing rules which cannot be defined using the declarative ModelSchemaItemDefinition interface.

Note: The addAttributeCheck method is a more handy way to register callbacks. Internally, it registers a listener to this event but comes with a simpler API and it is the recommended choice in most of the cases.

The checkAttribute method fires an event because it is decorated with it. Thanks to that you can use this event in various ways, but the most important use case is overriding the standard behavior of the checkAttribute() method. Let's see a typical listener template:

schema.on( 'checkAttribute', ( evt, args ) => {
	const context = args[ 0 ];
	const attributeName = args[ 1 ];
}, { priority: 'high' } );

The listener is added with a high priority to be executed before the default method is really called. The args callback parameter contains arguments passed to checkAttribute( context, attributeName ). However, the context parameter is already normalized to a ModelSchemaContext instance, so you do not have to worry about the various ways how context may be passed to checkAttribute().

So, in order to implement a rule "disallow bold in a text which is in a heading1, you can add such a listener:

schema.on( 'checkAttribute', ( evt, args ) => {
	const context = args[ 0 ];
	const attributeName = args[ 1 ];

	if ( context.endsWith( 'heading1 $text' ) && attributeName == 'bold' ) {
		// Prevent next listeners from being called.
		evt.stop();
		// Set the checkAttribute()'s return value.
		evt.return = false;
	}
}, { priority: 'high' } );

Allowing attributes in specific contexts will be a far less common use case, because it is normally handled by the allowAttributes rule from ModelSchemaItemDefinition. But if you have a complex scenario where bold should be allowed only in element foo which must be in element bar, then this would be the way:

schema.on( 'checkAttribute', ( evt, args ) => {
	const context = args[ 0 ];
	const attributeName = args[ 1 ];

	if ( context.endsWith( 'bar foo $text' ) && attributeName == 'bold' ) {
		// Prevent next listeners from being called.
		evt.stop();
		// Set the checkAttribute()'s return value.
		evt.return = true;
	}
}, { priority: 'high' } );

Parameters

eventInfo : EventInfo

An object containing information about the fired event.

args : tuple

The checkAttribute()'s arguments.

Event fired when the checkChild method is called. It allows plugging in additional behavior, for example implementing rules which cannot be defined using the declarative ModelSchemaItemDefinition interface.

Note: The addChildCheck method is a more handy way to register callbacks. Internally, it registers a listener to this event but comes with a simpler API and it is the recommended choice in most of the cases.

The checkChild method fires an event because it is decorated with it. Thanks to that you can use this event in various ways, but the most important use case is overriding standard behavior of the checkChild() method. Let's see a typical listener template:

schema.on( 'checkChild', ( evt, args ) => {
	const context = args[ 0 ];
	const childDefinition = args[ 1 ];
}, { priority: 'high' } );

The listener is added with a high priority to be executed before the default method is really called. The args callback parameter contains arguments passed to checkChild( context, child ). However, the context parameter is already normalized to a ModelSchemaContext instance and child to a ModelSchemaCompiledItemDefinition instance, so you do not have to worry about the various ways how context and child may be passed to checkChild().

Note: childDefinition may be undefined if checkChild() was called with a non-registered element.

So, in order to implement a rule "disallow heading1 in blockQuote", you can add such a listener:

schema.on( 'checkChild', ( evt, args ) => {
	const context = args[ 0 ];
	const childDefinition = args[ 1 ];

	if ( context.endsWith( 'blockQuote' ) && childDefinition && childDefinition.name == 'heading1' ) {
		// Prevent next listeners from being called.
		evt.stop();
		// Set the checkChild()'s return value.
		evt.return = false;
	}
}, { priority: 'high' } );

Allowing elements in specific contexts will be a far less common use case, because it is normally handled by the allowIn rule from ModelSchemaItemDefinition. But if you have a complex scenario where listItem should be allowed only in element foo which must be in element bar, then this would be the way:

schema.on( 'checkChild', ( evt, args ) => {
	const context = args[ 0 ];
	const childDefinition = args[ 1 ];

	if ( context.endsWith( 'bar foo' ) && childDefinition.name == 'listItem' ) {
		// Prevent next listeners from being called.
		evt.stop();
		// Set the checkChild()'s return value.
		evt.return = true;
	}
}, { priority: 'high' } );

Parameters

eventInfo : EventInfo

An object containing information about the fired event.

args : tuple

The checkChild()'s arguments.

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<ObservableSetEvent<number>>( '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<ObservableChangeEvent<number>>( '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: The 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 : TValue

The new property value.

oldValue : TValue

The previous property value.