Slab
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Form

Textarea

A multi-line text field built on the native textarea.

Element
<slab-textarea>
Built on
<textarea>
As Markdown
textarea.md

Example

Here's a styled version, <slab-styled-textarea>. 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
Shown to the crew on the morning of the pour.
HTML
<slab-styled-textarea label="Pour notes" placeholder="Weather, crew, anything unusual">
  <span slot="description">Shown to the crew on the morning of the pour.</span>
</slab-styled-textarea>
Shown to the crew on the morning of the pour.
HTML
<slab-textarea label="Pour notes" placeholder="Weather, crew, anything unusual">
  <span slot="description">Shown to the crew on the morning of the pour.</span>
</slab-textarea>

Usage

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

<slab-textarea label="Message" name="message" rows="4" maxlength="500"></slab-textarea>

Behavior

A multi-line text field with no visual styles, around a native textarea, so it is typed into, focused, and read the way one is.

The label and the textarea 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 textarea.

Validity is the native textarea's. required, minlength and maxlength are passed through to it, and whatever it decides is mirrored onto the host, so valueMissing, tooShort and tooLong all mean what they mean on a <textarea>. Nothing is computed twice.

Enter inserts a line break rather than submitting the form, as it does on a <textarea>.

rows and cols are passed through, so the textarea has the size a <textarea> with them would before any styles apply. wrap isn't. wrap="hard" only changes what a native textarea submits, and the host submits value itself, so it would do nothing.

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

API

<slab-textarea>

Attributes
Name Type Default Description
label Required string
autocomplete HTMLTextAreaElement['autocomplete']
cols number
disabled boolean false
hide-label boolean false
maxlength number
minlength number
name string ''
placeholder string
readonly boolean false
required boolean false
rows number
value string '' Like a native textarea's content, the attribute is the default value and the property is the current one, so the attribute doesn't change as the field is typed into.
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
resetValidityFeedback(): void Clears the validity feedback without changing validity.
select(): void
setCustomValidity(message: string): void
setSelectionRange(start: number, end: number, direction?: 'forward' | 'backward' | 'none'): void
setValidity(flags?: ValidityStateFlags, message?: string): void
Events
Name Type Description
input Event
change Event
Slots
Name Type Description
description Element | string
CSS parts
Name Description
description Text about the field, and its validity message when it has one
label The label
textarea
validity-message

Copy and own it

<slab-styled-textarea> 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.

textarea.ts 
import { customElement } from 'lit/decorators.js';
import Textarea from 'slab-elements/textarea.js';
import textInput from './text-input.styles.js';
import tokens from './tokens.styles.js';

declare global {
  interface HTMLElementTagNameMap {
    'slab-styled-textarea': StyledTextarea;
  }
}

/**
 * Textarea, styled: Text Field's look, taller, and resizable up and down.
 */
@customElement('slab-styled-textarea')
export default class StyledTextarea extends Textarea {
  static override styles = [tokens, textInput];
}
text-input.styles.ts 
import { css } from 'lit';

/*
  The look shared by everything typed into: Text Field, Textarea, Number, Date
  Field and Combobox, whose fields are "::part(input)", or "::part(textarea)"
  for Textarea. File Drop starts from it too, for its label and description.
*/
export default css`
  :host {
    color: var(--ink);
    display: grid;
    font-family: var(--font-body);
  }

  [part~='label'] {
    font-family: var(--font-display);
    font-size: 1.0625rem;
    font-weight: 600;
    margin-block-end: 0.375rem;
  }

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

  [part~='input'],
  [part~='textarea'] {
    background-color: var(--paper);
    block-size: 3rem;
    border: var(--border);
    border-radius: 0;
    box-sizing: border-box;
    color: inherit;
    font: inherit;

    /* A fixed height, shared with Select, so fields line up in a row. */
    padding: 0 0.75rem;
    transition:
      background-color 100ms,
      border-color 100ms,
      box-shadow 100ms,
      translate 100ms;

    &::placeholder {
      color: var(--ash);
    }

    /*
      The outline is transparent rather than gone, so it still shows in forced
      colors, where box shadows don't.
    */
    &:focus-visible {
      box-shadow: 4px 4px 0 var(--ember);
      outline: 2px solid transparent;
      translate: -2px -2px;
    }

    &:disabled {
      background-color: var(--chalk);
      border-style: dashed;
      color: var(--ash);
      cursor: not-allowed;
    }
  }

  [part~='textarea'] {
    block-size: auto;
    min-block-size: 7rem;
    padding: 0.625rem 0.75rem;
    resize: vertical;
  }

  :host(:state(readonly)) [part~='input'],
  :host(:state(readonly)) [part~='textarea'] {
    background-color: var(--chalk);
  }

  :host(:state(error)) [part~='input'],
  :host(:state(error)) [part~='textarea'] {
    border-color: var(--ember-deep);
  }

  /*
    Spaced by what's in it rather than by a gap, so a description with
    nothing in it takes no room, and a control beside the field lines up
    with its bottom edge.
  */
  [part~='description'] {
    color: var(--ash);
    display: grid;
    font-size: 0.875rem;
  }

  ::slotted([slot='description']) {
    margin-block-start: 0.375rem;
  }

  [part~='validity-message'] {
    color: var(--ember-deep);
    font-weight: 600;
    margin-block-start: 0.375rem;

    &::before {
      content: '■ ' / '';
    }
  }

  @media (prefers-reduced-motion: reduce) {
    [part~='input'],
    [part~='textarea'] {
      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);
  }
`;