# HelperText

> Helper or validation copy below form controls. Only the error state carries semantics (role=alert); warning, success and info differ by colour and an icon with no text alternative.

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

## When to use

HelperText is the supporting line under a form control: a neutral hint, or a semantic error, warning, success, or info message with an auto-resolved icon. The system's inputs render it automatically via their helperText and error props; reach for it directly only when composing a custom field.

## When not to use

- Do not render multiple `state="error"` HelperTexts under one field; multiple live regions create overlapping announcements. Consolidate.
- Do not use HelperText for page-level messages. AlertBanner and Toast exist for that scope.

## Look-alikes

- Text: Do not label form fields with Text; use Label (htmlFor) and HelperText (aria-describedby).

## Props

| Prop | Type | Default | Description | Required |
| --- | --- | --- | --- | --- |
| `children` | `React.ReactNode` | none | The helper text content to display. | Yes |
| `id` | `string` | none | Optional ID for aria-describedby association. | No |
| `className` | `string` | none | Additional CSS class name. | No |
| `state` | `"info" \| "success" \| "warning" \| "error"` | none | Semantic state of the helper text (error, warning, success, info). Warning, success and info icons carry a translated text alternative, so the state is not conveyed by colour alone. Default is neutral/no state. | No |

## Variants

- Allowed `state` values: `info`, `success`, `warning`, `error`.

## Invalid combinations

The contract records no invalid combinations.

## Keyboard

The contract records no keyboard interaction.

## 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 | ARIA: Link to control via id / aria-describedby. | Not yet verified: no evidence record. WCAG 4.1.2. |
| MUST | ARIA: Warning, success and info prefix the copy with a visually hidden, translated state word ("Warning:", "Success:", "Info:"; `helperText.state.*`), so the state is not conveyed by colour and icon alone (WCAG 1.3.1, 1.4.1) | Not yet verified: no evidence record. WCAG 4.1.2. |
| MUST | ARIA: Error renders role=alert and no state word: error copy states the problem itself. | 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 | A human completed an end-to-end accessibility review of this component. | Manual review, last on 2026-11-04. |
| SHOULD | Prefer the built-in helperText and error props on TextInput, TextArea, Select, Checkbox, and Switch; they render HelperText and wire aria-describedby for you. | Not stated in the contract. |
| SHOULD | Pass an id and reference it from the control's aria-describedby when composing manually, so the hint is announced with the field. | Not stated in the contract. |
| SHOULD | Keep it to one short sentence; longer guidance belongs in surrounding copy, not under the field. | Not stated in the contract. |
| SHOULD | Use state=error for validation failures; the paragraph becomes role=alert and announces immediately. The warning, success and info states add no semantics, so their copy must state the meaning in words. | Not stated in the contract. |
| SHOULD NOT | Do not put validation errors inside the Label; errors belong below the field, the label carries the field name. | Not stated in the contract. |
| SHOULD NOT | Do not hide the hint while an error shows; render the error HelperText above the hint and keep both visible, as FieldShell does for every system field. | Not stated in the contract. |

## Install and import

- Install: `npm install @digitaltableteur/react` (version 0.9.1, restricted access on npm).
- Import: `import { HelperText } 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-helper-text>`; see the custom elements manifest.

## Links

- Machine-readable contract (Design System Contract 1.0): https://www.digitaltableteur.com/contracts/v1/HelperText.contract.json
- Markdown version of this page: https://www.digitaltableteur.com/design-system/components/helper-text.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.