Textarea

Styles a multi-line text input with themed border, hover, focus, invalid, and disabled states on the host <textarea> element. Optionally auto-resizes to fit content.

Props

Prop	Type	Default	Description
`color`	`ValueOrState<ThemeColor>`	`"neutral"`	Theme color tone for the border and text.
`accentColor`	`ValueOrState<ThemeColor>`	`"primary"`	Theme color tone for the hover/focus outline.
`autoResize`	`boolean`	`false`	When `true`, grows the textarea height to fit its content on input.

Customization

Must see the source of patch at the bottom of each patch page to understand the structure then code it still code as html native element.

There are four levels of customization, in increasing order of effort:

Patch props. Each patch exposes a small, stable set of props—typically fewer than five. Lowest friction.
Context attributes. Use dataTone, dataSize, and dataDensity on a container to shift tone, size, or density for an entire subtree without touching individual elements.
Inline override. Native-wins merge strategy: any property set directly on the element overrides the patch value.
Create a variant. Clone a similar patch and edit it. Use this only when you need a reusable custom version.

Formulas

Unit - U = fontSize / 4 - convert final values with themeSpacing(n).

Size - n = intrinsic text lines, w = wrapping level, d = density factor:

height        = (n * 6 + 2 * d * w) * U
paddingBlock  = d * w * U
paddingInline = ceil(3 / w) * d * w * U
radius        = d * w * U

Base density d = 1.5:

U	w=0	w=1	w=2	w=3
height (`n = 1`)	6	9	12	15
paddingBlock	0	1.5	3	4.5
paddingInline	3	4.5	6	4.5
radius	0	1.5	3	4.5

Tone - K = N / 2 where N is the palette length. For N = 18, K = 9.

Role	Shift	n=0
Background	parent +/- n	0
Text	bg + K	6
Border	bg + K/2	3
Hover	bg + 2K/3	4
Selected / Focus	above +/- K/3	2-4

State shift range: K/3 <= delta <= 2K/3.

textarea

import { type PartialElement, toState, type ValueOrState } from "@domphy/core";
import {
  type ThemeColor,
  themeColor,
  themeDensity,
  themeSize,
  themeSpacing,
} from "@domphy/theme";
import { focusRing } from "../utils/focusRing.js";

/**
 * Styles a multi-line text input (border, focus/hover/invalid/disabled states)
 * on the host `<textarea>` element, with optional auto-resize to content.
 *
 * @hostTag textarea
 * @param props.color - Theme color for the border and text. Optional, accepts a value or state. Defaults to `"neutral"`.
 * @param props.accentColor - Theme color for hover/focus outline. Optional, accepts a value or state. Defaults to `"primary"`.
 * @param props.autoResize - When true, grows the textarea height to fit its content on input. Optional. Defaults to `false`.
 * @example { textarea: null, $: [textarea({ autoResize: true })] }
 */
function textarea(
  props: {
    color?: ValueOrState<ThemeColor>;
    accentColor?: ValueOrState<ThemeColor>;
    autoResize?: boolean;
  } = {},
): PartialElement {
  const color = toState(props.color ?? "neutral", "color");
  const accentColor = toState(props.accentColor ?? "primary", "accentColor");
  const { autoResize = false } = props;

  return {
    _onInsert: (node) => {
      if (node.tagName !== "textarea") {
        console.warn(`"textarea" primitive patch must use textarea tag`);
      }
    },
    _onMount: (node) => {
      if (autoResize) {
        const el = node.domElement as HTMLTextAreaElement;
        el.style.overflow = "hidden";
        const resize = () => {
          el.style.height = "auto";
          el.style.height = `${el.scrollHeight}px`;
        };
        el.addEventListener("input", resize);
        resize();
        node.addHook("Remove", () => el.removeEventListener("input", resize));
      }
    },
    style: {
      fontFamily: "inherit",
      lineHeight: "inherit",
      resize: "vertical",
      paddingInline: (listener) => themeSpacing(themeDensity(listener) * 2),
      paddingBlock: (listener) => themeSpacing(themeDensity(listener) * 1.5),
      border: "none",
      borderRadius: (listener) => themeSpacing(themeDensity(listener) * 1.5),
      fontSize: (listener) => themeSize(listener, "inherit"),
      color: (listener) => themeColor(listener, "text", color.get(listener)),
      outlineOffset: "-1px",
      outline: (listener) =>
        `1px solid ${themeColor(listener, "border-strong", color.get(listener))}`,
      backgroundColor: (listener) =>
        themeColor(listener, "inherit", color.get(listener)),
      transition: "outline-color 140ms ease, box-shadow 140ms ease",
      "&::placeholder": {
        color: (listener) => themeColor(listener, "shift-7"),
      },
      "&:hover:not([disabled]):not([aria-busy=true])": {
        outline: (listener) =>
          `1px solid ${themeColor(listener, "shift-5", accentColor.get(listener))}`,
      },
      "&:focus-visible": {
        boxShadow: (listener) => focusRing(listener, accentColor.get(listener)),
      },
      "&:invalid": {
        outline: (listener) =>
          `${themeSpacing(0.5)} solid ${themeColor(listener, "shift-5", "error")}`,
      },
      "&[disabled]": {
        opacity: 0.7,
        cursor: "not-allowed",
        color: (listener) => themeColor(listener, "muted", "neutral"),
        outline: (listener) =>
          `1px solid ${themeColor(listener, "border-strong", "neutral")}`,
        backgroundColor: (listener) =>
          themeColor(listener, "shift-2", "neutral"),
      },
    },
  };
}

export { textarea };

Textarea#

Props#

Textarea

Props