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guideHighlight

The highlight feature lets you mark text fragments with different colors. You can use it both as a marker (to change the background color) and as a pen (to change the text color).

# Demo

Select the text you want to highlight. Then use the highlight toolbar button Highlight to choose a desired color from the dropdown.

This demo only presents a limited set of features. Visit the feature-rich editor example to see more in action.

# Configuring the highlight options

The highlight feature comes with flexible configuration options.

However, the plugin has a predefined and limited number of available colors. It also focuses more on functionality than aesthetics. To change the text and background colors, use the font color and background color plugin.

Note that the highlight feature uses inline <mark> elements in the view.

It is possible to configure which highlight options are supported by the editor.
You can use the highlight.options configuration and define your own highlight styles.

For example, the following editor supports only two styles (a green marker and a red pen):

ClassicEditor
    .create( document.querySelector( '#editor' ), {
        highlight: {
            options: [
                {
                    model: 'greenMarker',
                    class: 'marker-green',
                    title: 'Green marker',
                    color: 'var(--ck-highlight-marker-green)',
                    type: 'marker'
                },
                {
                    model: 'redPen',
                    class: 'pen-red',
                    title: 'Red pen',
                    color: 'var(--ck-highlight-pen-red)',
                    type: 'pen'
                }
            ]
        },
        toolbar: [
            'heading', '|', 'bulletedList', 'numberedList', 'highlight', 'undo', 'redo'
        ]
    } )
    .then( /* ... */ )
    .catch( /* ... */ );

# Inline buttons

Instead of using the (default) 'highlight' button, the feature also supports a configuration with separate buttons available directly in the toolbar:

ClassicEditor
    .create( document.querySelector( '#editor' ), {
        toolbar: {
            items: [
                'heading',
                '|',
                'highlight:yellowMarker', 'highlight:greenMarker', 'highlight:pinkMarker',
                'highlight:greenPen', 'highlight:redPen', 'removeHighlight',
                '|',
                'undo', 'redo'
            ]
        }
    } )
    .then( /* ... */ )
    .catch( /* ... */ );

# Colors and styles

See the plugin options to learn more about defaults.

# Using CSS variables

The highlight feature is using the power of CSS variables which are defined in the stylesheet. Thanks to that, both the UI and the content styles share the same color definitions which can be easily customized:

:root {
    /* Make green a little darker. */
    --ck-highlight-marker-green: #199c19;

    /* Make the yellow more "dirty". */
    --ck-highlight-marker-yellow: #cac407;

    /* Make red more pinkish. */
    --ck-highlight-pen-red: #ec3e6e;
}

# Inline color definitions

It is possible to use inline color values in the rgba(R, G, B, A), #RRGGBB[AA], or hsla(H, S, L, A) formats instead of CSS variables. To do that, customize the options and define the color property for each option:

ClassicEditor
    .create( document.querySelector( '#editor' ), {
        highlight: {
            options: [
                {
                    model: 'greenMarker',
                    class: 'marker-green',
                    title: 'Green marker',
                    color: 'rgb(25, 156, 25)',
                    type: 'marker'
                },
                {
                    model: 'yellowMarker',
                    class: 'marker-yellow',
                    title: 'Yellow marker',
                    color: '#cac407',
                    type: 'marker'
                },
                {
                    model: 'redPen',
                    class: 'pen-red',
                    title: 'Red pen',
                    color: 'hsl(343, 82%, 58%)',
                    type: 'pen'
                }
            ]
        },
        toolbar: [
            'heading', '|', 'bulletedList', 'numberedList', 'highlight', 'undo', 'redo'
        ]
    } )
    .then( /* ... */ )
    .catch( /* ... */ );

Then, update the classes in the stylesheet so the content corresponds to the UI of the editor. It is recommended that the UI buttons and the actual highlights in the text are the same color.

.marker-green {
    background-color: rgb(25, 156, 25);
}
.marker-yellow {
    background-color: #cac407;
}
.pen-red {
    color: hsl(343, 82%, 58%);
}

# Installation

The highlight feature is enabled by default in the superbuild only.

To add this feature to your editor install the @ckeditor/ckeditor5-highlight package:

npm install --save @ckeditor/ckeditor5-highlight

And add it to your plugin list and the toolbar configuration:

import { Highlight } from '@ckeditor/ckeditor5-highlight';

ClassicEditor
    .create( document.querySelector( '#editor' ), {
        plugins: [ Highlight, /* ... */ ],
        toolbar: [ 'highlight', /* ... */ ]
    } )
    .then( /* ... */ )
    .catch( /* ... */ );

Read more about installing plugins.

CKEditor 5 has more features that can help you style your content:

# Common API

The Highlight plugin registers:

  • The 'highlight' dropdown,

  • The 'highlight' command.

    The number of options and their names correspond to the highlight.options configuration option.

    You can change the highlight of the current selection by executing the command with a desired value:

    editor.execute( 'highlight', { value: 'yellowMarker' } );

    The value corresponds to the model property in the configuration object. For the default configuration:

    highlight.options = [
    { model: 'yellowMarker', class: 'marker-yellow', title: 'Yellow Marker', color: 'var(--ck-highlight-marker-yellow)', type: 'marker' },
    { model: 'greenMarker', class: 'marker-green', title: 'Green marker', color: 'var(--ck-highlight-marker-green)', type: 'marker' },
    { model: 'pinkMarker', class: 'marker-pink', title: 'Pink marker', color: 'var(--ck-highlight-marker-pink)', type: 'marker' },
    { model: 'blueMarker', class: 'marker-blue', title: 'Blue marker', color: 'var(--ck-highlight-marker-blue)', type: 'marker' },
    { model: 'redPen', class: 'pen-red', title: 'Red pen', color: 'var(--ck-highlight-pen-red)', type: 'pen' },
    { model: 'greenPen', class: 'pen-green', title: 'Green pen', color: 'var(--ck-highlight-pen-green)', type: 'pen' }
]

    the 'highlight' command will accept the corresponding strings as values:

    • 'yellowMarker' – available as the 'highlight:yellowMarker' button,
    • 'greenMarker' – available as the 'highlight:greenMarker' button,
    • 'pinkMarker' – available as the 'highlight:pinkMarker' button,
    • 'blueMarker' – available as the 'highlight:blueMarker' button,
    • 'redPen' – available as the 'highlight:redPen' button,
    • 'greenPen' – available as the 'highlight:greenPen' button.

    Passing an empty value will remove any highlight attribute from the selection:

    editor.execute( 'highlight' );

We recommend using the official CKEditor 5 inspector for development and debugging. It will give you tons of useful information about the state of the editor such as internal data structures, selection, commands, and many more.

# Contribute

The source code of the feature is available on GitHub at https://github.com/ckeditor/ckeditor5/tree/master/packages/ckeditor5-highlight.