Slab
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Form

Switch

An on and off toggle built on a native checkbox with the switch role.

Element
<slab-switch>
Built on
<input type=checkbox role=switch>
As Markdown
switch.md

Example

Here's a styled version, <slab-styled-switch>. It's not in the package — it's an example of what you can build with the headless element. Copy it and make it yours at the bottom of this page. Switch to "As it ships" to see the same markup with the headless element and no CSS at all. That's your starting point.

Styled example As it ships
A plastic sheet under the slab keeps ground moisture out. Keep the slab above 50 °F while it cures.
HTML
<div class="stack">
  <slab-styled-switch label="Vapor barrier" checked>
    <span slot="description">A plastic sheet under the slab keeps ground moisture out.</span>
  </slab-styled-switch>
  <slab-styled-switch label="Cold-weather blankets">
    <span slot="description">Keep the slab above 50 °F while it cures.</span>
  </slab-styled-switch>
</div>
A plastic sheet under the slab keeps ground moisture out. Keep the slab above 50 °F while it cures.
HTML
<div class="stack">
  <slab-switch label="Vapor barrier" checked>
    <span slot="description">A plastic sheet under the slab keeps ground moisture out.</span>
  </slab-switch>
  <slab-switch label="Cold-weather blankets">
    <span slot="description">Keep the slab above 50 °F while it cures.</span>
  </slab-switch>
</div>

Usage

Install
pnpm add slab-elements lit
HTML
<script type="module">
  import 'slab-elements/switch.js';
</script>

<slab-switch label="Notifications" name="notifications" checked></slab-switch>

Keyboard

Key What it does
Space Turns it on or off.

Behavior

A switch with no visual styles, around a native checkbox, so it is checked, focused, and read the way one is.

The label and the switch are both in the shadow root, so a plain for reference names it without crossing out of one. The host delegates focus, so clicking anywhere on it, or a <label for> pointing at it, focuses the switch.

Style it through its parts and through :state(checked), :state(disabled), and :state(required). Where the label sits relative to the switch is layout, so it's left to the styles around it.

API

<slab-switch>

Attributes
Name Type Default Description
label Required string
checked boolean false Like a native checkbox, the attribute is the default state and the property is the current one, so the attribute doesn't change as the switch is toggled. Style :state(checked) rather than [checked].
disabled boolean false
hide-label boolean false
name string ''
required boolean false
value string 'on'
version string
Properties
Name Type Description
form Read-only HTMLFormElement | null
validity Read-only ValidityState
Methods
Signature Description
checkValidity(): boolean
click(): void
focus(options?: FocusOptions): void
reportValidity(): boolean
Events
Name Type Description
input Event
change Event
Slots
Name Type Description
description Element | string Text about the switch, such as a hint or an error
CSS parts
Name Description
description Text about the switch, such as a hint or an error
input
label The label
switch The switch itself

Copy and own it

<slab-styled-switch> isn't in the package. It's an example — copy it into your project and change whatever you want. Under the hood, it's just the headless element, subclassed, with styles set. That's it. Keyboard, focus, ARIA, forms, and events all come from the headless element, and the styles only reach in through ::part() and :state(), same as yours would.

To use it, copy these files, swap the tag in @customElement() for one of your own, and import it. tokens.styles.ts holds the colors and fonts every styled example shares, so you only need it once.

switch.ts 
import { customElement } from 'lit/decorators.js';
import Switch from 'slab-elements/switch.js';
import styles from './switch.styles.js';
import tokens from './tokens.styles.js';

declare global {
  interface HTMLElementTagNameMap {
    'slab-styled-switch': StyledSwitch;
  }
}

/**
 * Switch, styled: a settings row with the label on the left and a square
 * thumb that slides across a track, which turns ember when it's on.
 */
@customElement('slab-styled-switch')
export default class StyledSwitch extends Switch {
  static override styles = [tokens, styles];
}
switch.styles.ts 
import { css } from 'lit';

export default css`
  :host {
    align-items: center;
    color: var(--ink);
    column-gap: 1rem;
    display: grid;
    font-family: var(--font-body);
    grid-template-columns: 1fr auto;
  }

  :host(:state(disabled)) {
    color: var(--ash);
  }

  [part~='label'] {
    cursor: pointer;
    font-family: var(--font-display);
    font-size: 1.0625rem;
    font-weight: 600;
  }

  :host(:state(required)) [part~='label']::after {
    color: var(--ember-deep);
    content: ' *' / '';
  }

  [part~='switch'] {
    display: flex;
  }

  /*
    The input is the track, and the thumb is a square of background drawn on
    it, so there's nothing to position and nothing else to focus.
  */
  [part~='input'] {
    appearance: none;
    background:
      linear-gradient(var(--ink), var(--ink)) no-repeat 0.25rem 50% / 1.125rem
        1.125rem,
      var(--paper);
    block-size: 1.75rem;
    border: var(--border);
    cursor: pointer;
    inline-size: 3.25rem;
    margin: 0;
    transition: background 150ms;

    &:focus-visible {
      outline: 3px solid var(--ember);
      outline-offset: 2px;
    }

    &:checked {
      background:
        linear-gradient(var(--paper), var(--paper)) no-repeat
          calc(100% - 0.25rem) 50% / 1.125rem 1.125rem,
        var(--ember);
    }

    &:disabled {
      border-style: dashed;
      cursor: not-allowed;
      opacity: 0.5;
    }
  }

  [part~='description'] {
    color: var(--ash);
    display: block;
    font-size: 0.875rem;
    grid-column: 1 / -1;
  }

  @media (prefers-reduced-motion: reduce) {
    [part~='input'] {
      transition: none;
    }
  }
`;
tokens.styles.ts 
import { css } from 'lit';

/*
  The styled components' palette and type, taken from the logo: ink for the
  courses, ember for the base, paper behind them.

  Each is a short alias for a "--slab-styled-*" property, with the default as
  its fallback. Retheming is "--slab-styled-ember" and the rest on ":root",
  which every shadow root inherits. Were the defaults declared under those
  names here instead, each host's own declaration would shadow the page's.

  Each default is "light-dark()", so the components follow the page's
  "color-scheme": "dark" for dark, "light" for light, and "light dark" to
  follow the operating system. Ink and paper trade places in the dark, so
  ink is always the text and paper always what's behind it. Contrast is given
  as light, then dark.
*/
export default css`
  :host {
    /* Secondary text. 6.8:1 and 6.9:1 on paper. */
    --ash: var(--slab-styled-ash, light-dark(#5e5a55, #a8a19a));
    --border: 2px solid var(--ink);

    /* Behind disabled and read-only controls, and hovered rows. */
    --chalk: var(--slab-styled-chalk, light-dark(#f4f1ec, #2b2926));

    /*
      The logo's orange, brighter in the dark. 4.25:1 and 5.2:1 on paper is
      enough for borders, fills and large text, but not always for small text,
      which takes "--ember-deep".
    */
    --ember: var(--slab-styled-ember, light-dark(#d9492a, #ec5f3b));

    /*
      Orange for small text on paper, and for paper text on it. 5.7:1 and
      7.4:1.
    */
    --ember-deep: var(--slab-styled-ember-deep, light-dark(#b3381a, #ff8566));
    --font-body: var(
      --slab-styled-font-body,
      'IBM Plex Sans',
      system-ui,
      sans-serif
    );
    --font-display: var(
      --slab-styled-font-display,
      'Zilla Slab',
      rockwell,
      'Roboto Slab',
      serif
    );
    --font-mono: var(
      --slab-styled-font-mono,
      'IBM Plex Mono',
      ui-monospace,
      monospace
    );
    --ink: var(--slab-styled-ink, light-dark(#1c1c1c, #f4f1ec));
    --paper: var(--slab-styled-paper, light-dark(#fff, #1a1918));

    /* The hard, offset shadow a raised surface casts. */
    --shadow: 4px 4px 0 var(--ink);
  }
`;