FontSizePicker is a React component that renders a UI that allows users to select a font size.
The component renders a user interface that allows the user to select predefined (common) font sizes and contains an option that allows users to select custom font sizes (by choosing the value) if that functionality is enabled.

Usage

import { useState } from 'react';
import { FontSizePicker } from '@wordpress/components';
import { __ } from '@wordpress/i18n';

const fontSizes = [
    {
        name: __( 'Small' ),
        slug: 'small',
        size: 12,
    },
    {
        name: __( 'Big' ),
        slug: 'big',
        size: 26,
    },
];
const fallbackFontSize = 16;

const MyFontSizePicker = () => {
    const [ fontSize, setFontSize ] = useState( 12 );

    return (
        <FontSizePicker
            __next40pxDefaultSize
            fontSizes={ fontSizes }
            value={ fontSize }
            fallbackFontSize={ fallbackFontSize }
            onChange={ ( newFontSize ) => {
                setFontSize( newFontSize );
            } }
        />
    );
};

...

<MyFontSizePicker />

Props

The component accepts the following props:

disableCustomFontSizes: boolean

If true, it will not be possible to choose a custom fontSize. The user will be forced to pick one of the pre-defined sizes passed in fontSizes.

• Required: no
• Default: false

fallbackFontSize: number

If no value exists, this prop defines the starting position for the font size picker slider. Only relevant if withSlider is true.

• Required: No

fontSizes: FontSize[]

An array of font size objects. The object should contain properties size, name, and slug.
The property size contains a number with the font size value, in px or a string specifying the font size CSS property that should be used eg: “13px”, “1em”, or “clamp(12px, 5vw, 100px)”.
The name property includes a label for that font size e.g.: Small.
The slug property is a string with a unique identifier for the font size. Used for the class generation process.

Note: The slugs default and custom are reserved and cannot be used.

• Required: No
• Default: []

onChange: ( value: number | string | undefined, selectedItem?: FontSize ) => void

A function that receives the new font size value.
If onChange is called without any parameter, it should reset the value, attending to what reset means in that context, e.g., set the font size to undefined or set the font size a starting value.

• Required: Yes

size: 'default' | '__unstable-large'

Size of the control.

• Required: No
• Default: 'default'

units: string[]

Available units for custom font size selection.

• Required: No
• Default: [ 'px', 'em', 'rem', 'vw', 'vh' ]

value: number | string

The current font size value.

Note: For the units property to work, the current font size value must be specified as strings with units (e.g., '12px' instead of 12). When the font size is provided as a number, the component operates in “unitless mode” where the units property has no effect.

• Required: No

valueMode: 'literal' | 'slug'

Determines how the value prop should be interpreted.

• 'literal': The value prop contains the actual font size value (number or string).
• 'slug': The value prop contains the slug of the selected font size.

• Required: No

• Default: 'literal'

withReset: boolean

If true, a reset button will be displayed alongside the input field when a custom font size is active. Has no effect when disableCustomFontSizes is true.

• Required: no
• Default: true

withSlider: boolean

If true, a slider will be displayed alongside the input field when a custom font size is active. Has no effect when disableCustomFontSizes is true.

• Required: no
• Default: false

__next40pxDefaultSize: boolean

Start opting into the larger default height that will become the default size in a future version.

• Required: No
• Default: false