form-radiogroup.html html

<form-radiogroup value="other">
	<fieldset>
		<legend>Gender</legend>
		<label>
			<input type="radio" name="gender" value="female" />
			<span>Female</span>
		</label>
		<label>
			<input type="radio" name="gender" value="male" />
			<span>Male</span>
		</label>
		<label class="selected">
			<input type="radio" name="gender" value="other" checked />
			<span>Other</span>
		</label>
	</fieldset>
</form-radiogroup>

<form-radiogroup value="all" class="split-button">
	<fieldset>
		<legend class="visually-hidden">Filter</legend>
		<label class="selected">
			<input
				type="radio"
				class="visually-hidden"
				name="filter"
				value="all"
				checked
			/>
			<span>All</span>
		</label>
		<label>
			<input
				type="radio"
				class="visually-hidden"
				name="filter"
				value="active"
			/>
			<span>Active</span>
		</label>
		<label>
			<input
				type="radio"
				class="visually-hidden"
				name="filter"
				value="completed"
			/>
			<span>Completed</span>
		</label>
	</fieldset>
</form-radiogroup>

form-radiogroup.css css

form-radiogroup {
	display: inline-block;

	> fieldset {
		display: flex;
		gap: var(--space-m);
		border: none;
		margin: 0;
		padding: var(--space-xs) 0 var(--space-s);
	}

	& legend,
	& label {
		font-size: var(--font-size-s);
	}

	& label {
		border-radius: var(--space-xs);

		&:has(:focus-visible) {
			box-shadow: 0 0 var(--space-xxs) 2px var(--color-selection);
		}

		& input:focus {
			outline: none;
			box-shadow: none;
		}
	}

	&.split-button {
		& fieldset {
			gap: 0;
			padding: 0;
		}

		& label {
			display: inline-block;
			box-sizing: border-box;
			height: var(--input-height);
			min-width: var(--input-height);
			border: 1px solid var(--color-border);
			border-radius: 0;
			border-left-width: 0;
			background-color: var(--color-secondary);
			color: var(--color-text);
			padding: var(--space-xs) var(--space-s);
			cursor: pointer;
			line-height: var(--line-height-s);
			opacity: var(--opacity-dimmed);
			transition: opacity var(--transition-short) var(--easing-inout);

			&:hover {
				background-color: var(--color-secondary-hover);
				opacity: var(--opacity-solid);
			}

			&:active {
				background-color: var(--color-secondary-active);
			}

			&:focus-within {
				z-index: 1;
			}

			&.selected {
				color: var(--color-text-inverted);
				background-color: var(--color-primary);
				border-color: var(--color-primary-active);

				&:hover {
					background-color: var(--color-primary-hover);
				}

				&:active {
					background-color: var(--color-primary-active);
				}
			}
		}

		& legend + label {
			border-radius: var(--space-xs) 0 0 var(--space-xs);
			border-left-width: 1px;
		}

		& label:last-child {
			border-radius: 0 var(--space-xs) var(--space-xs) 0;
		}
	}
}

form-radiogroup.ts ts

import {
	type Component,
	component,
	fromDOM,
	fromEvents,
	getProperty,
	setAttribute,
	setProperty,
	toggleClass,
} from '../../..'
import { manageFocusOnKeydown } from '../../functions/event-listener/manage-focus-on-keydown'

export type FormRadiogroupProps = {
	readonly value: string
}

export default component(
	'form-radiogroup',
	{
		value: fromEvents(
			'input',
			{
				change: ({ target }) => target.value,
				keyup: ({ event, target }) => {
					if (event.key === 'Enter') target.click()
				},
			},
			fromDOM({ 'input:checked': getProperty('value') }, ''),
		),
	},
	(el, { all, useElements }) => {
		const radios = useElements('input')

		return [
			setAttribute('value'),
			all('input', [
				setProperty('tabIndex', target =>
					target.value === el.value ? 0 : -1,
				),
				...manageFocusOnKeydown(radios, inputs =>
					inputs.findIndex(input => input.checked),
				),
			]),
			all('label', [
				toggleClass(
					'selected',
					target => el.value === target.querySelector('input')?.value,
				),
			]),
		]
	},
)

declare global {
	interface HTMLElementTagNameMap {
		'form-radiogroup': Component<FormRadiogroupProps>
	}
}