# TextInput

> Labeled text input with validation, helper text, and size tokens.

- Status: stable
- Group: form
- Page: https://www.digitaltableteur.com/design-system/components/text-input
- Contract: https://www.digitaltableteur.com/contracts/v1/TextInput.contract.json

## When to use

TextInput is the standard single-line field: label, control, helper and error text in one component. The email and tel types add built-in validation (typo suggestions for common email domains, libphonenumber formatting for phone numbers); error renders above the helper line and wires aria-invalid.

## When not to use

- Do not ship a form that relies on the email validator as the only verification step. The validator is for UX; the server must verify too.
- Do not pass a `value` plus a `defaultValue`. The component treats `value` as controlled; mixing them produces drift.
- Do not use TextInput for multi-line text. Use **TextArea**, which shares the label + helper contract but carries multi-line UX.

## Look-alikes

- Combobox: Do not use Combobox for free text with suggestions; it only emits option values (no free-solo mode). Use TextInput plus your own suggestion list.
- PhoneInput: Do not use TextInput type=tel for international audiences; you lose country selection and normalization.
- Select: Do not use Select for a freeform value with suggestions; use TextInput.
- TextArea: Do not build multi-line entry with TextInput; use TextArea.

## Props

| Prop | Type | Default | Description | Required |
| --- | --- | --- | --- | --- |
| `label` | `string` | none | Visible field label; also feeds the input name (lowercased, spaces to hyphens) unless a name prop is passed. | Yes |
| `type` | `"number" \| "search" \| "text" \| "tel" \| "email" \| "date" \| "time" \| "password" \| "datetime-local" \| "month" \| "week"` | none | Native HTML input type. Telephone values format as the user types; telephone and email values validate when the field first loses focus and then live as the value changes. Date/time variants retain the browser's localized picker and ISO-compatible submitted value. | Yes |
| `size` | `"sm" \| "md" \| "lg" \| "S" \| "M" \| "L"` | `md` | Size variant for input. Defaults to `md`. | No |
| `onValueChange` | `(value: string \| number) => void` | none | Value change handler (recommended) | No |
| `defaultValue` | `string \| number` | none | Initial value for uncontrolled component. | No |
| `value` | `string \| number` | none | Controlled value; an initial "" is treated as absent (uncontrolled), later changes always sync in. | No |
| `error` | `string` | none | Validation error message; renders above the helper line and sets aria-invalid. | No |
| `status` | `FieldStatus` | none | Semantic state: colours the border and styles statusMessage. `error` overrides it. | No |
| `statusMessage` | `string` | none | Message under the field for `status`, above the helper line. | No |
| `actions` | `FieldAction[]` | none | Icon buttons at the end of the label row: each runs an operation or opens a menu. | No |
| `helperText` | `string` | none | Helper copy below the field. | No |
| `disabled` | `boolean` | `false` | Disables the input. Declared explicitly (not just via the native attribute extension) so the agent-blocks prop extraction sees it. | No |
| `clearable` | `boolean` | `false` | Shows a labelled ×-button inside the field chrome while the field has a value; clearing returns focus to the input. Defaults to `false`. | No |
| `onClear` | `() => void` | none | Called after the clear button empties the field (onValueChange also fires with "") | No |
| `hideLabel` | `boolean` | `false` | Visually hides the label (kept in the accessibility tree); use where surrounding design carries the affordance. Defaults to `false`. | No |
| `width` | `"full" \| "2ch" \| "3ch" \| "4ch" \| "5ch" \| "10ch" \| "20ch" \| "30ch"` | `full` | Widest the field grows, in characters of the expected answer (after the GOV.UK input widths): "10ch" for a code, "30ch" for an email address. The field still shrinks with its container. Defaults to `full`. | No |
| `onChange` | `(value: string \| number) => void` | none | No description in the contract. Deprecated: Deprecated. | No |

## Variants

- Available sizes: `sm`, `md`, `lg` (default `md`). Forwarded to CSS module size classes.
- Available types: `number`, `search`, `text`, `tel`, `email`, `date`, `time`, `password`, `datetime-local`, `month`, `week`.
- Allowed `width` values: `full`, `2ch`, `3ch`, `4ch`, `5ch`, `10ch`, `20ch`, `30ch` (default `full`).

## Invalid combinations

- MUST NOT: `value` and `defaultValue` set together. `value` makes the component controlled and `defaultValue` uncontrolled; pass one, not both.

## Keyboard

| Key | Behaviour |
| --- | --- |
| Tab | Moves focus to the control and on to the next focusable element. (standard) |

Rows marked (standard) name a key the contract lists without a description; the behaviour shown is the usual one for that key.

## Rules

Every item under When not to use is a MUST NOT. MUST and SHOULD follow RFC 2119.

| Level | Rule | How it is checked |
| --- | --- | --- |
| MUST NOT | `value` and `defaultValue` set together. `value` makes the component controlled and `defaultValue` uncontrolled; pass one, not both. | Checked by the MCP tool validate_component_usage. |
| MUST | ARIA: Label association. | Not yet verified: no evidence record. WCAG 4.1.2. |
| MUST | ARIA: Aria-describedby for error/helper; a consumer aria-describedby is merged after the status and helper ids, while a consumer aria-invalid replaces the computed one. | Not yet verified: no evidence record. WCAG 4.1.2. |
| MUST | ARIA: Built-in email and tel validation waits for the first blur, then re-runs on every change; the error renders through HelperText with role=alert, so a half-typed value is not announced and the error clears as soon as the value is valid. | Not yet verified: no evidence record. WCAG 4.1.2. |
| MUST | ARIA: Clear button carries a per-field accessible name and returns focus to the input. | Not yet verified: no evidence record. WCAG 4.1.2. |
| MUST | Required stories produce no axe violations at the configured severity. | Automated by `npm run test:stories:matrix:ci`. WCAG 2.5.8. |
| MUST | The accessibility tree (role, name, state) matches the committed snapshot for every required story. | Automated by `npm run test:stories:matrix:ci`. WCAG 1.3.1, 4.1.2. |
| MUST | The component remains legible and operable under a real browser forced-colors: active pass. | Automated by `npm run test:stories:hc`. |
| MUST | Every documented keyboard interaction works as specified. | Not yet verified: no evidence record. WCAG 2.1.1, 2.1.2. |
| MUST | A human completed an end-to-end accessibility review of this component. | Manual review, last on 2026-11-04. |
| SHOULD | Always pass a real label; placeholders vanish on focus and are not accessible names. | Not stated in the contract. |
| SHOULD | Read values through onValueChange; it hands you the typed value directly (onChange is deprecated). | Not stated in the contract. |
| SHOULD | Pick the semantic type; email and tel get validation and the right mobile keyboard for free. | Not stated in the contract. |
| SHOULD | Use helperText for format hints before errors happen (We never share this address). | Not stated in the contract. |
| SHOULD | Use clearable for fields users iterate on (search boxes, filters, generators); the ×-button appears only while there is a value and hands focus back to the input. | Not stated in the contract. |
| SHOULD | Reserve hideLabel for dense compositions where surrounding design carries the affordance; the label stays in the accessibility tree, so still write a real one. | Not stated in the contract. |
| SHOULD NOT | Do not build multi-line entry with TextInput; use TextArea. | Not stated in the contract. |
| SHOULD NOT | Do not layer your own live email/tel validation on top of the built-in one; two messages can disagree. Server-side truth belongs in error after submit. | Not stated in the contract. |

## Install and import

- Install: `npm install @digitaltableteur/react` (version 0.9.1, restricted access on npm).
- Import: `import { TextInput } from "@digitaltableteur/react";`
- Entry point: `@digitaltableteur/react/forms` exports it too.
- Styles: import `@digitaltableteur/react/style.css` once at the app boundary.
- Also available as the custom element `<dt-text-input>`; see the custom elements manifest.

## Links

- Machine-readable contract (Design System Contract 1.0): https://www.digitaltableteur.com/contracts/v1/TextInput.contract.json
- Markdown version of this page: https://www.digitaltableteur.com/design-system/components/text-input.md
- Component index as JSON: https://www.digitaltableteur.com/design-system/components.json
- All components: https://www.digitaltableteur.com/design-system/components
- Source: The implementation lives in a private repository. This page, its Markdown twin and the contract are generated from it at build time and are the public source of truth.