UndoCommand (undo)

@ckeditor/ckeditor5-undo/src/undocommand

class

The undo command stores batches applied to the document and is able to undo a batch by reversing it and transforming by batches from history that happened after the reversed batch.

The undo command also takes care of restoring the document selection.

Filtering

Public
Inherited
Mixed
Protected
Private
Deprecated

Properties

editor : Editor

readonly inherited

The editor on which this command will be used.
isEnabled : Boolean

readonly inherited observable
Flag indicating whether a command is enabled or disabled. A disabled command will do nothing when executed.
A concrete command class should control this value by overriding the refresh() method.

It is possible to disable a command from "outside". For instance, in your integration you may want to disable a certain set of commands for the time being. To do that, you can use the fact that isEnabled is observable and it fires the set:isEnabled event every time anyone tries to modify its value:
```
function disableCommand( cmd ) {
    cmd.on( 'set:isEnabled', forceDisable, { priority: 'highest' } );

    cmd.isEnabled = false;

    // Make it possible to enable the command again.
    return () => {
        cmd.off( 'set:isEnabled', forceDisable );
        cmd.refresh();
    }

    function forceDisable( evt ) {
        evt.return = false;
        evt.stop();
    }
}

// Usage:

// Disabling the command.
const enableBold = disableCommand( editor.commands.get( 'bold' ) );

// Enabling the command again.
enableBold();
```
value

readonly inherited observable

The value of the command. A concrete command class should define what it represents for it.

For example, the 'bold' command's value indicates whether the selection starts in a bolded text. And the value of the 'link' command may be an object with links details.

It is possible for a command to have no value (e.g. for stateless actions such as 'imageUpload').

A concrete command class should control this value by overriding the refresh() method.
_createdBatches : WeakSet.<Batch>

protected inherited

Stores all batches that were created by this command.
_stack : Array

protected inherited
Stack of items stored by the command. These are pairs of:
- batch saved by the command,
- selection state at the moment of saving the batch.

Methods

constructor( editor )

inherited

Creates a new Command instance.

Parameters

editor : Editor

Editor on which this command will be used.
addBatch( batch )

inherited

Stores a batch in the command, together with the selection state of the document created by the editor which this command is registered to.

Parameters

batch : Batch

The batch to add.
bind( bindProperties ) → Object

inherited
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.
clearStack()

inherited

Removes all items from the stack.
decorate( methodName )

inherited
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

inherited
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()

inherited

Destroys the command.
execute( [ batch ] )
Executes the command. This method reverts a batch added to the command's stack, transforms and applies the reverted version on the document and removes the batch from the stack. Then, it restores the document selection.
Parameters

[ batch ] : Batch

A batch that should be undone. If not set, the last added batch will be undone.

Fires
- execute
- revert
Overrides: BaseCommand#execute
fire( eventOrInfo, [ args ] ) → *

inherited

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).
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.
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 {}
off( event, callback )

inherited

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] } )

inherited

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] } )

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.

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 {}
refresh()

inherited

Refreshes the command. The command should update its isEnabled and value properties in this method.

This method is automatically called when any changes are applied to the document.
set( name, [ value ] )

inherited

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

inherited
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 ] )

inherited
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 ] )

inherited
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.
_restoreSelection( ranges, isBackward, operations )

protected inherited

Restores the document selection state after a batch was undone.

Parameters

ranges : Array.<Range>

Ranges to be restored.

isBackward : Boolean

A flag describing whether the restored range was selected forward or backward.

operations : Array.<Operation>

Operations which has been applied since selection has been stored.
_undo( batchToUndo, undoingBatch )

protected inherited

Undoes a batch by reversing that batch, transforming reversed batch and finally applying it. This is a helper method for execute.

Parameters

batchToUndo : Batch

The batch to be undone.

undoingBatch : Batch

The batch that will contain undoing changes.

Events

change:isEnabled( eventInfo, name, value, oldValue )

inherited

Fired when the isEnabled property changed value.

Parameters

eventInfo : EventInfo

An object containing information about the fired event.

name : String

Name of the changed property (isEnabled).

value : Boolean

New value of the isEnabled property with given key or null, if operation should remove property.

oldValue : Boolean

Old value of the isEnabled property with given key or null, if property was not set before.
change:value( eventInfo, name, value, oldValue )

inherited

Fired when the value property changed value.

Parameters

eventInfo : EventInfo

An object containing information about the fired event.

name : String

Name of the changed property (value).

value : *

New value of the value property with given key or null, if operation should remove property.

oldValue : *

Old value of the value property with given key or null, if property was not set before.
change:{property}( eventInfo, name, value, oldValue )

inherited
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.
execute( eventInfo )

inherited

Event fired by the execute method. The command action is a listener to this event so it's possible to change/cancel the behavior of the command by listening to this event.

See decorate for more information and samples.

Note: This event is fired even if command is disabled. However, it is automatically blocked by a high priority listener in order to prevent command execution.

Parameters

eventInfo : EventInfo

An object containing information about the fired event.
revert( eventInfo )

Fired when execution of the command reverts some batch.

Parameters

eventInfo : EventInfo

An object containing information about the fired event.
set:{property}( eventInfo, name, value, oldValue )

inherited
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.

UndoCommand (undo)

Filtering

Properties

editor : Editormodule:undo/undocommand~UndoCommand#editor

isEnabled : Booleanmodule:undo/undocommand~UndoCommand#isEnabled

valuemodule:undo/undocommand~UndoCommand#value

_createdBatches : WeakSet.<Batch>module:undo/undocommand~UndoCommand#_createdBatches

_stack : Arraymodule:undo/undocommand~UndoCommand#_stack

Methods

constructor( editor )module:undo/undocommand~UndoCommand#constructor

Parameters

addBatch( batch )module:undo/undocommand~UndoCommand#addBatch

Parameters

bind( bindProperties ) → Objectmodule:undo/undocommand~UndoCommand#bind

Parameters

Returns

clearStack()module:undo/undocommand~UndoCommand#clearStack

decorate( methodName )module:undo/undocommand~UndoCommand#decorate

Parameters

delegate( events ) → EmitterMixinDelegateChainmodule:undo/undocommand~UndoCommand#delegate

Parameters

Returns

destroy()module:undo/undocommand~UndoCommand#destroy

execute( [ batch ] )module:undo/undocommand~UndoCommand#execute

Parameters

Fires

fire( eventOrInfo, [ args ] ) → *module:undo/undocommand~UndoCommand#fire

Parameters

Returns

listenTo( emitter, event, callback, [ options ] = { [options.priority] } )module:undo/undocommand~UndoCommand#listenTo

Parameters

off( event, callback )module:undo/undocommand~UndoCommand#off

Parameters

on( event, callback, [ options ] = { [options.priority] } )module:undo/undocommand~UndoCommand#on

Parameters

once( event, callback, [ options ] = { [options.priority] } )module:undo/undocommand~UndoCommand#once

Parameters

refresh()module:undo/undocommand~UndoCommand#refresh

set( name, [ value ] )module:undo/undocommand~UndoCommand#set

Parameters

stopDelegating( [ event ], [ emitter ] )module:undo/undocommand~UndoCommand#stopDelegating

Parameters

stopListening( [ emitter ], [ event ], [ callback ] )module:undo/undocommand~UndoCommand#stopListening

Parameters

unbind( [ unbindProperties ] )module:undo/undocommand~UndoCommand#unbind

Parameters

_restoreSelection( ranges, isBackward, operations )module:undo/undocommand~UndoCommand#_restoreSelection

Parameters

_undo( batchToUndo, undoingBatch )module:undo/undocommand~UndoCommand#_undo

Parameters

Events

change:isEnabled( eventInfo, name, value, oldValue )module:undo/undocommand~UndoCommand#event:change:isEnabled

Parameters

change:value( eventInfo, name, value, oldValue )module:undo/undocommand~UndoCommand#event:change:value

Parameters

change:{property}( eventInfo, name, value, oldValue )module:undo/undocommand~UndoCommand#event:change:{property}

Parameters

execute( eventInfo )module:undo/undocommand~UndoCommand#event:execute

Parameters

revert( eventInfo )module:undo/undocommand~UndoCommand#event:revert

Parameters

set:{property}( eventInfo, name, value, oldValue )module:undo/undocommand~UndoCommand#event:set:{property}

Parameters

`editor : Editor`

`isEnabled : Boolean`

`value`

`_createdBatches : WeakSet.<Batch>`

`_stack : Array`

`constructor( editor )`

`addBatch( batch )`

`bind( bindProperties ) → Object`

`clearStack()`

`decorate( methodName )`

`delegate( events ) → EmitterMixinDelegateChain`

`destroy()`

`execute( [ batch ] )`

`fire( eventOrInfo, [ args ] ) → *`

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

`off( event, callback )`

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

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

`refresh()`

`set( name, [ value ] )`

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

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

`unbind( [ unbindProperties ] )`

`_restoreSelection( ranges, isBackward, operations )`

`_undo( batchToUndo, undoingBatch )`

`change:isEnabled( eventInfo, name, value, oldValue )`

`change:value( eventInfo, name, value, oldValue )`

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

`execute( eventInfo )`

`revert( eventInfo )`

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