Field ​

Features ​

• Generates and wires up ids/aria-describedby/aria-invalid automatically.
• Works with a plain native input, or with existing reka controls (Checkbox, Select, DateField, ...) placed inside it.
• Sync or async custom validation, with `onSubmit`/`onBlur`/`onChange` timing and optional debounce.
• Validates `required` on non-native controls (Checkbox, Select, DateField) too.
• Reads native constraint-validation state (`required`, `pattern`, `type=email`, ...) automatically.
• Exposes `data-valid`/`data-invalid`/`data-dirty`/`data-touched`/`data-filled`/`data-focused` on every part for styling.
• Shows the browser's validation message by default, or your own per failing constraint.
• Fully additive — every reka control behaves exactly as before when used outside a Field.

Installation ​

Install the component from your command line.

$ npm add reka-ui

Anatomy ​

Import all parts and piece them together.

<script setup>
import { FieldControl, FieldDescription, FieldError, FieldLabel, FieldRoot, FieldValidity } from 'reka-ui'
</script>

<template>
  <FieldRoot>
    <FieldLabel />
    <FieldControl />
    <FieldDescription />
    <FieldError />
    <FieldValidity />
  </FieldRoot>
</template>

API Reference ​

Root ​

Contains all the parts of a field, provides shared ids, and runs validation. Renders a div by default.

Exposes a validate() method through a template ref, which validates the field regardless of validationMode and returns whether it's valid. A disabled field skips validation.

Every part (and a participating reka control) renders the same data attributes, so any of them can be styled by the field's state.

Label ​

Renders a Label, automatically wired to the control via for/id and the control's aria-labelledby.

For a button control like SelectTrigger, a native label forwards clicks and :hover to the button. Render another element with :native-label="false" instead: it drops for and focuses the control on click.

<FieldLabel as="div" :native-label="false">
  Fruit
</FieldLabel>

Control ​

A native form control (input by default — pass as="textarea" or as="select" for others). Binds id/name/disabled/required/aria-labelledby/aria-describedby/aria-invalid from the Field, and reports focus/blur/input interactions back to it. The Field's name takes precedence over the control's; disabled and required apply when set on either.

Bind its value with v-model, or set a starting value with default-value. A controlled value is validated when it changes, so a value you reject or rewrite never reaches the field.

Existing reka controls (CheckboxRoot, SelectRoot/SelectTrigger, DateFieldRoot, ...) can be used directly inside a FieldRoot instead of FieldControl — they pick up the same wiring automatically by optionally reading the Field's context, and behave exactly as before when used outside a Field.

Description ​

A description for the field, automatically added to the control's aria-describedby. Renders a p by default.

Error ​

An error message for the field, added to the control's aria-describedby while shown. Renders a div by default.

• Without match, it shows whenever the field is invalid. Its default content is the current message: a server error, a custom validate message, or the browser's validation message. Several messages render as a list.
• With a ValidityState key like match="valueMissing", it shows only for that constraint, typically with your own message.
• With match set to true, it always shows, letting an external library control it.

It never shows while the field is disabled. Its data-state is open or closed, and it waits for a closing animation before unmounting, keeping its last message meanwhile.

Validity ​

Renders no element. Passes the field's validity, errors, error, value and initialValue to its slot, for displaying something custom based on the field's validity.

<FieldValidity v-slot="{ validity, error }">
  <p v-if="validity.valid === false">
    {{ error }}
  </p>
</FieldValidity>

Examples ​

Custom validation ​

Pass a sync or async validate function. It receives the control's value and, inside a FormRoot, the values of every named field. Return a message (or array of messages) when invalid, or null/undefined when valid. An async validate doesn't prevent form submission in onSubmit mode.

<script setup>
import { FieldControl, FieldError, FieldLabel, FieldRoot } from 'reka-ui'

async function checkUsername(value) {
  const isTaken = await api.isUsernameTaken(value)
  return isTaken ? 'That username is already taken.' : null
}
</script>

<template>
  <FieldRoot name="username" :validate="checkUsername" validation-mode="onBlur">
    <FieldLabel>Username</FieldLabel>
    <FieldControl />
    <FieldError v-slot="{ errors }">
      {{ errors[0] }}
    </FieldError>
  </FieldRoot>
</template>

Validation timing ​

Use validation-mode to control when validation (native constraint checks and the custom validate function) runs. Whatever the mode, an empty required field isn't reported until the user has changed its value, or the form is submitted:

• onSubmit (default): when the owning FormRoot submits, then on every change after that.
• onBlur: when the control loses focus.
• onChange: on every change to the control's value. Use validation-debounce-time to wait between validate calls.

A FieldRoot without its own validation-mode uses the FormRoot's.

<template>
  <FieldRoot
    name="email"
    validation-mode="onChange"
    :validation-debounce-time="300"
  >
    <!-- ... -->
  </FieldRoot>
</template>

Using an existing reka control ​

Place any reka form control inside a FieldRoot instead of FieldControl — it participates automatically.

<script setup>
import { FieldDescription, FieldLabel, FieldRoot, SelectContent, SelectItem, SelectPortal, SelectRoot, SelectTrigger, SelectValue, SelectViewport } from 'reka-ui'
</script>

<template>
  <FieldRoot name="fruit" required>
    <FieldLabel>Fruit</FieldLabel>
    <SelectRoot>
      <SelectTrigger>
        <SelectValue placeholder="Select a fruit" />
      </SelectTrigger>
      <SelectPortal>
        <SelectContent>
          <SelectViewport>
            <SelectItem value="apple">
              Apple
            </SelectItem>
          </SelectViewport>
        </SelectContent>
      </SelectPortal>
    </SelectRoot>
    <FieldDescription>Pick your favorite.</FieldDescription>
  </FieldRoot>
</template>

Participating controls report focus/dirty/filled state, pass their actual value to validate, and enforce required: an empty Select, an unchecked Checkbox or an empty DateField makes the field invalid (match="valueMissing").

Accessibility ​

FieldLabel associates with the control via matching for/id and aria-labelledby. FieldDescription and any shown FieldError are added to the control's aria-describedby, and aria-invalid is set once the field is known to be invalid. Custom errors are also set on native controls with setCustomValidity, so the browser's own validity state agrees with the field.