GeneralHtmlSupportConfig

The configuration of allowed content rules used by General HTML Support.

Setting this configuration option will enable HTML features that are not explicitly supported by any other dedicated CKEditor 5 features.

const htmlSupportConfig.allow = [
	{
		name: 'div',                      // Enable 'div' element support,
		classes: [ 'special-container' ], // allow 'special-container' class,
		styles: 'background',             // allow 'background' style,
		attributes: true                  // allow any attribute (can be empty).
	},
	{
		name: 'p',                                   // Extend existing Paragraph feature,
		classes: 'highlighted'                       // with 'highlighted' class,
		attributes: [
			{ key: 'data-i18n-context, value: true } // and i18n attribute.
		]
	}
];

The configuration of allowed empty inline elements that should not be removed.

Note that you should also add an appropriate entry to allow list.

const htmlSupportConfig.allowEmpty = [ 'i', 'span' ];

The configuration of disallowed content rules used by General HTML Support.

Setting this configuration option will disable listed HTML features.

const htmlSupportConfig.disallow = [
	{
		name: /[\s\S]+/    // For every HTML feature,
		attributes: {
			key: /^on.*$/ // disable 'on*' attributes, like 'onClick', 'onError' etc.
		}
	}
];

The configuration of the Full page editing feature. The option is used by the FullPage feature.

ClassicEditor
	.create( {
		htmlSupport: {
			fullPage: ... // Full page feature config.
		}
	} )
	.then( ... )
	.catch( ... );

Controls the sandbox attribute on iframe elements by specifying allowed sandbox flags.

Note: This option only affects the editing view and does not modify the data output.

When set to false:

• The sandbox attribute will not be modified or added to iframe elements.

When set to true:

• All restrictions are enforced by adding an empty sandbox attribute to iframe elements.

When set to an array of strings:

• Only the specified sandbox flags will be preserved on iframe elements.
• Any sandbox flags not in the list will be automatically removed.
• If an empty array is provided, the sandbox attribute will be added with no flags (enforcing all restrictions).

ClassicEditor
	.create( {
		htmlSupport: {
			// All restrictions are enforced (empty sandbox attribute).
			htmlIframeSandbox: true
		}
	} )
	.then( ... )
	.catch( ... );

Defaults to true

Whether a filler text (non-breaking space entity —  ) will be inserted into empty block elements in HTML output. This is used to render block elements properly with line-height.

When set to true, empty blocks will be preserved in the editing view. When false (default), empty blocks are only preserved in the data output.

The option is used by the EmptyBlock feature.

Defaults to false