OTP Input — Stimeo UI

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The stimeo--otp controller streamlines the creation of highly usable and accessible multi-segment numeric passcode entry inputs popular in Multi-Factor Authentication (MFA). It supports keyboard roving and validation pattern checks, auto-advances focus on valid inputs, steps back and clears previous cells on Backspace, and splits pasted multi-digit text across segmented fields seamlessly. Dispatches stimeo--otp:complete once all fields are successfully filled.

running

Please enter the 6-digit authentication code

Keyboard

Key	Action
`Backspace`	If the current field is empty, moves focus to the previous field and clears its content.
`←`	Moves focus to the previous input field.
`→`	Moves focus to the next input field.
`Home`	Moves focus to the first input field.
`End`	Moves focus to the last input field.

<%# Markup for the otp (OTP PIN passcode) demo.
    Provides auto-advance on entry in each field, Backspace to go back, paste
    distribution, and value sync. %>
<div
  class="otp-demo"
  id="otp-passcode"
  data-controller="stimeo--otp"
  data-stimeo--otp-length-value="6"
  data-stimeo--otp-pattern-value="[0-9]"
  role="group"
  aria-label="<%= t("components.otp.demo.label") %>"
>
  
  <div class="otp-demo__label"><%= t("components.otp.demo.label") %></div>
  
  <div class="otp-demo__fields">
    <% 6.times do |i| %>
      <input
        class="otp-demo__field"
        type="text"
        inputmode="numeric"
        maxlength="1"
        data-stimeo--otp-target="field"
        data-action="
          input->stimeo--otp#onInput
          keydown->stimeo--otp#onKeydown
          paste->stimeo--otp#onPaste
        "
        aria-label="<%= t("components.otp.demo.digit_label", position: i + 1) %>"
      />
    <% end %>
  </div>

  <input
    type="hidden"
    data-stimeo--otp-target="value"
    name="otp"
  />

  <%# Region for invalid-input / full-width-character warning messages. %>
  <div
    data-stimeo--otp-target="error"
    id="otp-error-message"
    class="otp-demo__error"
    role="alert"
    aria-live="polite"
    hidden
  >
    <span class="otp-demo__error-badge">!</span>
    <span class="otp-demo__error-text">
      <%= t("components.otp.demo.invalid_msg") %>
    </span>
  </div>

  <%# Placeholder for the completion celebration message. %>
  <div id="otp-complete-message" class="otp-demo__message" style="display: none;">
    <span class="otp-demo__success-badge">✓</span>
    <span class="otp-demo__success-text">
      <%= t("components.otp.demo.complete_msg") %>
      <strong id="otp-success-code"></strong>
    </span>
  </div>
</div>

/*
 * Presentation-only styles for the otp demo.
 * Whether a field is filled switches on data-filled (set by the library).
 */

.otp-demo {
  display: inline-block;
  font-family: inherit;
}

.otp-demo__label {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--color-text-muted);
  margin-bottom: 0.5rem;
}

.otp-demo__fields {
  display: flex;
  gap: 0.5rem;
}

.otp-demo__field {
  width: 3rem;
  height: 3.5rem;
  text-align: center;
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--fg);
  background: var(--surface-card);
  border: 1px solid var(--border-strong);
  border-radius: 8px;
  outline: none;
  transition: all 0.15s ease;
}

/* Filled state (data-filled). */
.otp-demo__field[data-filled="true"] {
  border-color: var(--border-interactive);
}

/* Focus state. */
.otp-demo__field:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(var(--accent-rgb), 0.15);
}

.otp-demo__message {
  margin-top: 1rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.75rem 1rem;
  background: var(--leaf-50);
  border: 1px solid var(--leaf-50);
  border-radius: 8px;
  animation: otpFadeIn 0.25s cubic-bezier(0.16, 1, 0.3, 1);
}

.otp-demo__success-badge {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 1.25rem;
  height: 1.25rem;
  border-radius: 50%;
  background: var(--leaf-500);
  color: var(--white);
  font-size: 0.75rem;
  font-weight: bold;
}

.otp-demo__success-text {
  font-size: 0.875rem;
  color: var(--leaf-500);
}

.otp-demo__error {
  margin-top: 1rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.75rem 1rem;
  background: var(--danger-50);
  border: 1px solid var(--ruby-200);
  border-radius: 8px;
  animation: otpFadeIn 0.25s cubic-bezier(0.16, 1, 0.3, 1);
}

/* Stimeo controls visibility only via the hidden attribute (behavior only); the styling reads
   that state. */
.otp-demo__error[hidden] {
  display: none;
}

.otp-demo__error-badge {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 1.25rem;
  height: 1.25rem;
  border-radius: 50%;
  background: var(--danger-500);
  color: var(--white);
  font-size: 0.75rem;
  font-weight: bold;
}

.otp-demo__error-text {
  font-size: 0.875rem;
  color: var(--color-accent);
}

@keyframes otpFadeIn {
  from {
    opacity: 0;
    transform: translateY(4px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

// Demo script that catches the complete event and shows a celebration message.
document.getElementById('otp-passcode').addEventListener('stimeo--otp:complete', function (e) {
  const msg = document.getElementById('otp-complete-message');
  const code = document.getElementById('otp-success-code');
  if (msg && code) {
    code.textContent = e.detail.value;
    msg.style.display = 'flex';
  }
});

// Hide the message when the value changes.
// Backspace clears values programmatically in the controller, so the native input
// event doesn't fire — subscribe to stimeo--otp:change instead.
document.getElementById('otp-passcode').addEventListener('stimeo--otp:change', function (e) {
  const fields = Array.from(document.querySelectorAll('.otp-demo__field'));
  const filled = fields.every((f) => f.value.length > 0);
  if (!filled) {
    const msg = document.getElementById('otp-complete-message');
    if (msg) msg.style.display = 'none';
  }
});

These demo styles use shared design tokens (light + dark). Copy the shared styles too, then toggle data-theme on your root element for dark mode.

The data-* attributes you add to your own HTML to wire this component. Put the data-controller below on a root element, then place its targets / values / actions inside that element.

On the root element data-controller="stimeo--otp"

Targets

Name	Description	Attribute
`field` required	A single-character digit input; one per slot, focus auto-advances between them.	`data-stimeo--otp-target="field"`
`value`	Hidden input that holds the concatenated code for form submission.	`data-stimeo--otp-target="value"`
`error`	Element shown/hidden to surface an invalid-input state.	`data-stimeo--otp-target="error"`

Values

Name	Description	Attribute
`length`	Number of digits / fields in the code (default 6).	`data-stimeo--otp-length-value`
`pattern`	Per-character validation regex (default `[0-9]`).	`data-stimeo--otp-pattern-value`

Actions

Name	Description	Action
`onInput`	Validates the typed character, marks the field filled, and advances focus.	`stimeo--otp#onInput`
`onKeydown`	Handles Backspace clearing/stepping back and Arrow/Home/End navigation.	`stimeo--otp#onKeydown`
`onPaste`	Intercepts a paste and distributes its valid characters across the fields.	`stimeo--otp#onPaste`

Events

Name	Description	Event
`change`	Dispatched whenever the combined value changes, with that value in detail.	`stimeo--otp:change`
`complete`	Dispatched when all fields are filled, with the full value in detail.	`stimeo--otp:complete`
`invalid`	Dispatched on a rejected character/paste, with the pattern in detail.	`stimeo--otp:invalid`

State hooks

The library only manages these ARIA/data attributes and custom properties. Your CSS reads them to render the look — selectors like [aria-selected], [aria-expanded], or var(--stimeo--…) hook into this state.

Hook	Target	Meaning
`data-filled`	individual input field	"true" when a digit is filled, removed otherwise.
`value`	hidden input target	Stores the final concatenated PIN code string synchronized on every input.