OTP Input

A segmented one-time password input that renders individual cells for each digit. Auto-advances focus between cells, supports paste, Backspace navigation, and fires completion events.

Features

⌫ Backspace Navigation — moves focus backward and clears the cell
⏭️ Auto-Advance — focus moves to the next cell automatically on input
➗ Optional Separator — visual divider between cells
🌈 6 Semantic Colors — primary, secondary, info, success, warning, error
🎨 5 Variants — solid, flat, bordered, outline, ghost
📋 Paste Support — pastes fill all cells at once
📏 3 Sizes — sm, md, lg
🔒 Masked Mode — renders • characters instead of input values
🔗 Form-Associated — name attribute & native form reset support
🔢 Configurable Length — any number of cells (default 6)
🔤 Two Input Types — numeric (digits only) or alphanumeric

Source Code

View Source Code

import { computed, define, html, inject, prop, signal, watch, onMounted } from '@vielzeug/craftit';
import { createListControl } from '@vielzeug/craftit/controls';

import type { ComponentSize, ThemeColor, VisualVariant } from '../../types';

import { colorThemeMixin, forcedColorsFocusMixin, sizeVariantMixin } from '../../styles';
import { disablableBundle, sizableBundle, themableBundle } from '../shared/bundles';
import { mountFormContextSync } from '../shared/dom-sync';
import { FORM_CTX } from '../shared/form-context';
import styles from './otp-input.css?inline';

export type BitOtpInputEvents = {
  change: { complete: boolean; originalEvent?: Event; value: string };
  complete: { originalEvent?: Event; value: string };
};

/** OTP Input props */
export type BitOtpInputProps = {
  /** Theme color */
  color?: ThemeColor;
  /** Make inputs disabled */
  disabled?: boolean;
  /** Accessible label */
  label?: string;
  /** Number of input cells */
  length?: number;
  /** Mask input (show dots instead of characters) */
  masked?: boolean;
  /** Form field name */
  name?: string;
  /** Show a separator in the middle (e.g. "–") */
  separator?: string;
  /** Component size */
  size?: ComponentSize;
  /** Input type: 'numeric' (digits only) or 'alphanumeric' */
  type?: 'numeric' | 'alphanumeric';
  /** Current value */
  value?: string;
  /** Visual variant */
  variant?: Exclude<VisualVariant, 'text' | 'frost' | 'glass'>;
};

/**
 * A segmented OTP (One-Time Password) input with N individual cells.
 * Auto-advances focus on input, auto-backs on Backspace, handles paste.
 *
 * @element bit-otp-input
 *
 * @attr {number} length - Number of cells (default: 6)
 * @attr {string} type - 'numeric' (default) | 'alphanumeric'
 * @attr {string} value - Current code value
 * @attr {boolean} disabled - Disable all cells
 * @attr {boolean} masked - Show as password
 * @attr {string} size - 'sm' | 'md' | 'lg'
 * @attr {string} color - Theme color
 * @attr {string} name - Form field name
 * @attr {string} label - Group aria-label
 * @attr {string} separator - Optional separator character shown in the middle
 *
 * @fires change - Emitted whenever a cell changes. detail: { value: string, complete: boolean, originalEvent?: Event }
 * @fires complete - Emitted when all cells are filled. detail: { value: string, originalEvent?: Event }
 *
 * @cssprop --otp-cell-size - Width and height of each cell
 * @cssprop --otp-cell-gap - Gap between cells
 * @cssprop --otp-cell-font-size - Font size inside cells
 * @cssprop --otp-cell-radius - Border radius of cells
 * @cssprop --otp-cell-border-color - Default border color
 * @cssprop --otp-cell-focus-border - Focused border color
 *
 * @part group - Group container.
 * @part cell - Shadow part for the `cell` element.
 * @example
 * ```html
 * <bit-otp-input length="6" color="primary"></bit-otp-input>
 * ```
 */
export const OTP_INPUT_TAG = define<BitOtpInputProps, BitOtpInputEvents>('bit-otp-input', {
  props: {
    ...themableBundle,
    ...sizableBundle,
    ...disablableBundle,
    label: 'One-time password',
    length: 6,
    masked: false,
    name: undefined,
    separator: undefined,
    type: prop.oneOf(['numeric', 'alphanumeric'] as const, 'numeric'),
    value: '',
    variant: undefined,
  },
  setup(props, { emit, host }) {
    const formCtx = inject(FORM_CTX);
    const lengthValue = computed(() => Number(props.length.value) || 6);
    const isDisabled = computed(() => Boolean(props.disabled.value) || Boolean(formCtx?.disabled.value));
    const cells = computed(() => Array.from({ length: lengthValue.value }, (_, i) => i));
    const focusedIndex = signal(0);
    const otpValue = signal(String(props.value.value || ''));
    const normalizedPropValue = () => String(props.value.value || '');

    host.bind({
      attr: {
        value: () => otpValue.value || null,
      },
    });

    mountFormContextSync(host.el, formCtx, props);

    function getInputs(): HTMLInputElement[] {
      return [...(host.el.shadowRoot?.querySelectorAll<HTMLInputElement>('input.cell') ?? [])];
    }

    const listControl = createListControl({
      getIndex: () => focusedIndex.value,
      getItems: () => getInputs(),
      keys: { next: ['ArrowRight'], prev: ['ArrowLeft'] },
      loop: false,
      setIndex: (index) => {
        focusedIndex.value = index;

        const inputs = getInputs();

        inputs[index]?.focus();
      },
    });

    function getValue(): string {
      return getInputs()
        .map((i) => i.value)
        .join('');
    }
    function syncInputsFromValue(raw: string) {
      const allInputs = getInputs();
      const normalized = String(raw || '').slice(0, allInputs.length);

      for (const input of allInputs) input.value = '';

      normalized.split('').forEach((c, i) => {
        if (allInputs[i]) allInputs[i].value = c;
      });

      otpValue.value = getValue();
    }
    function emitOtpState(originalEvent?: Event, forceComplete?: boolean): void {
      const allInputs = getInputs();
      const full = getValue();
      const complete = forceComplete ?? (full.length === allInputs.length && full.split('').every(Boolean));

      otpValue.value = full;
      emit('change', { complete, originalEvent, value: full });

      if (complete) emit('complete', { originalEvent, value: full });
    }
    function isAllowed(char: string): boolean {
      if (props.type.value === 'numeric') return /^\d$/.test(char);

      return /^[a-z\d]$/i.test(char);
    }
    function handleInput(e: Event, index: number) {
      const input = e.target as HTMLInputElement;
      let val = input.value;

      // Keep only last character if multiple were typed somehow
      if (val.length > 1) val = val.slice(-1);

      // Validate character
      if (val && !isAllowed(val)) {
        input.value = '';

        return;
      }

      input.value = val;

      const allInputs = getInputs();

      emitOtpState(e);

      // Auto-advance
      if (val && index < allInputs.length - 1) {
        allInputs[index + 1].focus();
        allInputs[index + 1].select();
      }
    }
    function handleKeydown(e: KeyboardEvent, index: number) {
      const input = e.target as HTMLInputElement;
      const allInputs = getInputs();

      focusedIndex.value = index;

      if (e.key === 'Backspace') {
        if (input.value) {
          input.value = '';
        } else if (index > 0) {
          const prevIndex = listControl.prev();
          const prevInput = allInputs[prevIndex];

          if (prevInput) {
            prevInput.select();
            prevInput.value = '';
          }
        }

        emitOtpState(e, false);
        e.preventDefault();
      } else {
        listControl.handleKeydown(e);
      }
    }
    function handlePaste(e: ClipboardEvent) {
      e.preventDefault();

      const pasted = e.clipboardData?.getData('text') ?? '';
      const chars = pasted
        .split('')
        .filter((c) => isAllowed(c))
        .slice(0, lengthValue.value);
      const allInputs = getInputs();

      chars.forEach((char, i) => {
        if (allInputs[i]) allInputs[i].value = char;
      });

      emitOtpState(e);

      // Focus the cell after last pasted char
      const focusIdx = Math.min(chars.length, allInputs.length - 1);

      allInputs[focusIdx]?.focus();
    }

    watch(props.value, (value) => {
      syncInputsFromValue(String(value || ''));
    });

    watch(props.length, () => {
      // Cells re-render when length changes; sync after DOM updates.
      requestAnimationFrame(() => syncInputsFromValue(normalizedPropValue()));
    });

    const separatorIdx = computed(() => {
      const len = Number(props.length.value) || 6;

      return props.separator.value != null ? Math.floor(len / 2) : -1;
    });

    onMounted(() => {
      // Populate cells from value prop on mount
      syncInputsFromValue(normalizedPropValue());
    });

    return () => html`
      <div class="otp-group" part="group" role="group" :aria-label="${props.label}">
        ${() =>
          cells.value.map(
            (i) => html`
              ${() =>
                separatorIdx.value > 0 && i === separatorIdx.value
                  ? html`<span class="separator" aria-hidden="true">${() => props.separator.value || '-'}</span>`
                  : ''}
              <input
                class="cell"
                part="cell"
                :type="${() => (props.masked.value ? 'password' : 'text')}"
                :inputmode="${() => (props.type.value === 'numeric' ? 'numeric' : 'text')}"
                maxlength="1"
                :autocomplete="${() => (i === 0 ? 'one-time-code' : 'off')}"
                :aria-label="${() => `Digit ${i + 1} of ${lengthValue.value}`}"
                :disabled="${() => (isDisabled.value ? true : null)}"
                :name="${() => (props.name.value ? `${props.name.value}[${i}]` : null)}"
                @input="${(e: Event) => handleInput(e, i)}"
                @keydown="${(e: KeyboardEvent) => handleKeydown(e, i)}"
                @paste="${(e: ClipboardEvent) => (i === 0 ? handlePaste(e) : e.preventDefault())}"
                @focus="${(e: FocusEvent) => (e.target as HTMLInputElement).select()}" />
            `,
          )}
      </div>
    `;
  },
  styles: [colorThemeMixin, sizeVariantMixin({}), forcedColorsFocusMixin('.cell'), styles],
});

Basic Usage

html

<bit-otp-input label="Verification code" color="primary"></bit-otp-input>

<script type="module">
  import '@vielzeug/buildit';
</script>

Listen for completion:

html

<bit-otp-input id="otp" label="Enter OTP" color="primary"></bit-otp-input>

<script type="module">
  import '@vielzeug/buildit';

  document.getElementById('otp').addEventListener('complete', (e) => {
    console.log('OTP complete:', e.detail.value);
  });
</script>

Length

Preview

Code

RTL

Types

Preview

Code

RTL

Masked Input

Use masked to hide the entered values (useful for PINs).

Preview

Code

RTL

With Separator

Use separator to add a visual divider between cells.

Preview

Code

RTL

Sizes

Preview

Code

RTL

Colors

Preview

Code

RTL

Variants

Preview

Code

RTL

Disabled

Preview

Code

RTL

API Reference

Attributes

Attribute	Type	Default	Description
`length`	`number`	`6`	Number of input cells
`type`	`'numeric' \| 'alphanumeric'`	`'numeric'`	Allowed character type
`value`	`string`	`''`	Current value (string of all cells concatenated)
`masked`	`boolean`	`false`	Render cells as hidden characters
`separator`	`boolean`	`false`	Show a visual divider between cells
`disabled`	`boolean`	`false`	Disable all cells
`label`	`string`	—	Accessible label for the group
`name`	`string`	—	Form field name
`color`	`'primary' \| 'secondary' \| 'info' \| 'success' \| 'warning' \| 'error'`	—	Focus ring / active cell color
`size`	`'sm' \| 'md' \| 'lg'`	`'md'`	Cell size
`variant`	`'solid' \| 'flat' \| 'bordered' \| 'outline' \| 'ghost'`	`'solid'`	Visual style variant

Events

Event	Detail	Description
`change`	`{ value: string, complete: boolean }`	Fired on every cell input
`complete`	`{ value: string }`	Fired when all cells have been filled

CSS Custom Properties

Property	Description
`--otp-cell-size`	Width and height of each cell
`--otp-cell-gap`	Gap between cells
`--otp-cell-font-size`	Font size inside each cell
`--otp-cell-radius`	Cell border radius
`--otp-cell-border-color`	Default cell border color
`--otp-cell-focus-border`	Cell border color when focused

Accessibility

The OTP input component follows WCAG 2.1 Level AA standards.

`bit-otp-input`

✅ Keyboard Navigation

Focus auto-advances to the next cell on valid input; Backspace moves back and clears the cell.
Tab moves focus out of the group; paste fills all cells at once.

✅ Screen Readers

Renders as a <fieldset> with a <legend> for the label attribute.
autocomplete="one-time-code" is set automatically on each cell input.
aria-disabled reflects the disabled state.

Best Practices

Do:

Always provide a label attribute to give context (e.g. "Verification code").
Use masked for PINs and security codes to prevent shoulder-surfing.
Listen to complete (not change) to trigger auto-submission after the last cell is filled.
Keep length at 4–8 cells — more cells increase cognitive load.

Don't:

Auto-submit without giving users a chance to review — show a confirmation step before sending.
Use alphanumeric for numeric-only codes (e.g. SMS OTPs) — numerics trigger the numeric keyboard on mobile.

Input — plain single-line input field

Usage Guide

Framework Integration

Theming

Examples

OTP Input

Features

Source Code

Basic Usage

Length

Types

Masked Input

With Separator

Sizes

Colors

Variants

Disabled

API Reference

Attributes

Events

CSS Custom Properties

Accessibility

`bit-otp-input`

Best Practices

OTP Input ​

Features ​

Source Code ​

Basic Usage ​

Length ​

Types ​

Masked Input ​

With Separator ​

Sizes ​

Colors ​

Variants ​

Disabled ​

API Reference ​

Attributes ​

Events ​

CSS Custom Properties ​

Accessibility ​

bit-otp-input ​

Best Practices ​

Related Components ​

OTP Input

Features

Source Code

Basic Usage

Length

Types

Masked Input

With Separator

Sizes

Colors

Variants

Disabled

API Reference

Attributes

Events

CSS Custom Properties

Accessibility

`bit-otp-input`

Best Practices

Related Components