custom-toggle-toolbar-button.adoc

Creating custom toggle toolbar buttons

A toggle button triggers an action when clicked and maintains an active state. This means it can be toggled on or off. The toggle button provides the user visual feedback of its state through CSS styling. An example of this behavior is the Bold button, which becomes highlighted when the cursor is within text that has bold formatting.

Options

Name	Value	Requirement	Description
text	string	optional	Text to display if no icon is found.
icon	string	optional	partial$misc/admon-predefined-icons-only.adoc
tooltip	string	optional	Text for button tooltip.
enabled	boolean	optional	default: true - Represents the button’s enabled state. When false, the button is unclickable. Can be changed using setEnabled from the button’s API.
active	boolean	optional	default: false - Represents the button’s active state. When true, the button is highlighted. Can be changed using setActive from the button’s API.
onSetup	(api) => (api) => void	optional	default: () => () => {} - Function invoked when the button is rendered. For details, see: Using onSetup.
onAction	(api) => void	required	Function invoked when the button is clicked.
shortcut	string	optional	Shortcut to display in the tooltip. To register a shortcut, see: Add custom shortcuts to {productname}.
context	string	optional	default: mode:design - The context property dynamically enables or disables the button based on the editor’s current state. For details, see: Context.

API

Name	Value	Description
isEnabled	() => boolean	Checks if the button is enabled.
setEnabled	(state: boolean) => void	Sets the button’s enabled state.
isActive	() => boolean	Checks if the button is in the active (toggled on) state.
setActive	(state: boolean) => void	Sets the button’s active (toggled) state.
setText	(text: string) => void	Sets the text label to display.
setIcon	(icon: string) => void	Sets the icon of the button.

Toggle button example and explanation

liveDemo::custom-toolbar-toggle-button[tab="js"]

The example above adds two custom strikethrough toggle buttons. Both buttons use the mceToggleFormat command to apply and remove strikethrough formatting. This command toggles a specified format on and off, but only works for formats already registered with the editor. In this example, strikethrough is the registered format.

Basic toggle: manual state management

The first (customStrikethrough) button applies and removes strikethrough formatting. Its state toggles upon click using api.setActive(!api.isActive()). However, this button does not reflect whether the selected content has strikethrough formatting which is its expected behavior. Moving the cursor into content with strikethrough formatting does not activate the button, and moving it out does not deactivate it.

State-synced toggle: automatic state updates

The second button (customToggleStrikethrough) addresses this by using editor.formatter.formatChanged in its onSetup callback to monitor the formatting state of the current selection.

Note	The format name passed to mceToggleFormat via editor.execCommand(command, ui, args) is the same as the one used in editor.formatter.formatChanged(formatName, callback).

The formatChanged method accepts the following parameters:

The formatChanged method accepts the following parameters:

• formats (String, required) — A comma-separated list of registered format names to monitor.

• callback (Function, required) — A function called when the formatting state changes. The callback receives a state boolean indicating whether the format is present (true) or absent (false) in the current selection.

• similar (Boolean, optional) — When true, treats all similar variants of the same format name as equivalent, regardless of variables. Defaults to false.

• vars (Object, optional) — When similar is false, specifies which format variables must match for the callback to execute.

The method returns an object with an unbind function. Calling unbind() removes the format listener, which is essential for cleanup when the button is destroyed.

In the example, onSetup first checks if the current selection matches strikethrough formatting using editor.formatter.match('strikethrough') and sets the initial active state accordingly. It then registers a formatChanged listener that calls api.setActive(state) whenever the strikethrough state changes. The teardown function returned from onSetup calls changed.unbind() to clean up the listener.

This approach ensures customToggleStrikethrough is highlighted whenever the cursor is within strikethrough-formatted content and deactivated when it is not, regardless of how the formatting was applied.

partial$misc/onSetup.adoc