# How to Validate Different OTP Input Types in Vue 3: A Complete Guide

> Master OTP validation in Vue 3 with vue3-otp-input. Learn to validate number, tel, letter-numeric, and password types using regex filters and keyboard restrictions.

- Repository: [Ejiro Asiuwhu/vue3-otp-input](https://github.com/ejirocodes/vue3-otp-input)
- Tags: how-to-guide
- Published: 2026-03-01

---

**The `vue3-otp-input` component validates OTP characters automatically based on the `input-type` prop, applying regex filters on paste and keyboard restrictions to ensure only allowed characters are entered.**

When building secure authentication flows in Vue 3, validating different OTP input types—such as numeric codes, alphanumeric tokens, or masked passwords—requires careful handling of both paste operations and keystroke filtering. The `ejirocodes/vue3-otp-input` library implements this validation internally through the `input-type` prop, letting you enforce constraints without writing custom validation logic.

## Supported Input Types and Validation Rules

The component supports four distinct input types, each with specific validation behavior defined in [`src/components/vue3-otp-input.vue`](https://github.com/ejirocodes/vue3-otp-input/blob/main/src/components/vue3-otp-input.vue) and [`src/components/single-otp-input.vue`](https://github.com/ejirocodes/vue3-otp-input/blob/main/src/components/single-otp-input.vue).

### Number (Digits Only)

When `input-type="number"`, the component restricts input to digits 0-9.

- **Paste validation**: The handler in [`vue3-otp-input.vue`](https://github.com/ejirocodes/vue3-otp-input/blob/main/vue3-otp-input.vue) checks the clipboard content against the regex `/^\d+$/` and rejects the paste if it contains non-numeric characters.
- **Keyboard validation**: The `handleOnKeyDown` method in [`single-otp-input.vue`](https://github.com/ejirocodes/vue3-otp-input/blob/main/single-otp-input.vue) blocks keys that are not digits or control characters (Backspace, Delete, Arrows, etc.).

### Letter-Numeric (Alphanumeric)

When `input-type="letter-numeric"`, the component accepts both letters and numbers.

- **Paste validation**: Uses the regex `/^\w+$/` to verify that pasted content contains only word characters (A-Z, a-z, 0-9, underscore).
- **Keyboard validation**: Permits letter keys and numeric keys while filtering out symbols.

### Tel (Default)

When `input-type="tel"` (the default), the component imposes no character restrictions.

- **Validation**: No regex filtering is applied during paste operations.
- **Behavior**: Only the length of each input field is limited. This mode is useful for generic PINs that might include symbols or spaces.

### Password (Masked Input)

When `input-type="password"`, the component masks the entered characters while following the same validation rules as `tel`.

- **HTML type**: The computed property `inputTypeValue` in [`single-otp-input.vue`](https://github.com/ejirocodes/vue3-otp-input/blob/main/single-otp-input.vue) maps the prop value to the HTML attribute `type="password"`, rendering dots or asterisks instead of characters.
- **Validation**: No character restrictions are enforced, identical to `tel` mode.

## Implementation Examples for Each Input Type

Below are practical implementations demonstrating how to configure the `input-type` prop for different validation scenarios.

### Numeric OTP (6-Digit Code)

```vue
<template>
  <v-otp-input
    v-model:value="otpCode"
    :num-inputs="6"
    input-type="number"
    @on-complete="handleComplete"
  />
</template>

<script setup lang="ts">
import { ref } from 'vue';
import VOtpInput from 'vue3-otp-input';

const otpCode = ref('');
const handleComplete = (value: string) => {
  console.log('Numeric OTP completed:', value);
};
</script>

```

### Alphanumeric OTP (5-Character Token)

```vue
<template>
  <v-otp-input
    v-model:value="token"
    :num-inputs="5"
    input-type="letter-numeric"
    @on-complete="verifyToken"
  />
</template>

<script setup lang="ts">
import { ref } from 'vue';
const token = ref('');

const verifyToken = (val: string) => {
  // Token contains only letters and numbers
  console.log('Alphanumeric token:', val);
};
</script>

```

### Password-Masked Input

```vue
<template>
  <v-otp-input
    v-model:value="secureCode"
    :num-inputs="4"
    input-type="password"
    @on-complete="submitSecure"
  />
</template>

<script setup lang="ts">
import { ref } from 'vue';
const secureCode = ref('');

const submitSecure = (val: string) => {
  console.log('Masked code entered');
};
</script>

```

## How Validation Works Under the Hood

Understanding the internal mechanics helps you debug validation issues and extend the component if needed.

### Paste Validation Logic

The wrapper component [`src/components/vue3-otp-input.vue`](https://github.com/ejirocodes/vue3-otp-input/blob/main/src/components/vue3-otp-input.vue) handles clipboard operations. When a user pastes content, the component checks the string against type-specific regex patterns:

- For `number`: `/^\d+$/` ensures only digits
- For `letter-numeric`: `/^\w+$/` ensures word characters only

If the pasted content fails the regex test, the paste event is rejected and the input fields remain unchanged.

### Keyboard Input Filtering

Individual input fields are managed by [`src/components/single-otp-input.vue`](https://github.com/ejirocodes/vue3-otp-input/blob/main/src/components/single-otp-input.vue). The `handleOnKeyDown` method (lines 85-91) implements keyboard-level validation by checking the key code before allowing the character to appear:

- **Numeric mode**: Blocks keys that are not digits (0-9) or control keys
- **Letter-numeric mode**: Allows letters (A-Z, a-z) and digits
- **Tel/Password modes**: Permits any printable character

This two-layer validation (paste + keyboard) ensures that invalid characters never enter the OTP fields, providing immediate feedback to users.

### Input Type Mapping

The computed property `inputTypeValue` in [`single-otp-input.vue`](https://github.com/ejirocodes/vue3-otp-input/blob/main/single-otp-input.vue) translates the abstract `input-type` prop into concrete HTML attributes:

- `password` maps to `type="password"` for masking
- Other types map to their corresponding HTML input types or default to text behavior

This mapping occurs at lines 5-9 of the single field component.

## Summary

- **Use `input-type="number"`** to restrict OTP entry to digits only; the component validates using `/^\d+$/` on paste and filters non-numeric keystrokes.
- **Use `input-type="letter-numeric"`** for alphanumeric codes; validation uses `/^\w+$/` to ensure only letters and numbers are accepted.
- **Use `input-type="tel"`** (default) when you need no character restrictions, only length limits.
- **Use `input-type="password"`** to mask characters visually while maintaining the same validation rules as `tel`.
- Validation occurs in two stages: paste handling in [`vue3-otp-input.vue`](https://github.com/ejirocodes/vue3-otp-input/blob/main/vue3-otp-input.vue) and keyboard filtering in [`single-otp-input.vue`](https://github.com/ejirocodes/vue3-otp-input/blob/main/single-otp-input.vue).

## Frequently Asked Questions

### What happens if a user pastes invalid characters into a numeric OTP field?

The component rejects the entire paste operation. In [`src/components/vue3-otp-input.vue`](https://github.com/ejirocodes/vue3-otp-input/blob/main/src/components/vue3-otp-input.vue), the paste handler tests the clipboard content against the regex `/^\d+$/` when `input-type="number"`. If the test fails, the event is prevented and the input fields remain unchanged, ensuring only valid digits enter the field.

### Can I use special characters like dashes or spaces in the OTP?

Only when using `input-type="tel"` or `input-type="password"`. These modes do not apply regex filters to pasted content or keystrokes, allowing any characters including dashes, spaces, or symbols. The `number` and `letter-numeric` types explicitly block special characters through regex validation (`/^\d+$/` and `/^\w+$/` respectively).

### How does the password input type differ from tel in terms of validation?

There is no difference in validation logic. Both `password` and `tel` accept any character without regex filtering. The distinction lies in the HTML rendering: [`single-otp-input.vue`](https://github.com/ejirocodes/vue3-otp-input/blob/main/single-otp-input.vue) computes `inputTypeValue` to apply `type="password"` to the underlying input element, which masks the characters visually while maintaining the permissive validation rules of `tel` mode.

### Is it possible to change the input type dynamically after the component mounts?

Yes, the `input-type` prop is reactive. Changing the prop value updates the validation rules immediately because [`vue3-otp-input.vue`](https://github.com/ejirocodes/vue3-otp-input/blob/main/vue3-otp-input.vue) and [`single-otp-input.vue`](https://github.com/ejirocodes/vue3-otp-input/blob/main/single-otp-input.vue) reference the prop directly in their paste handlers and keydown listeners. However, existing values in the input fields are not retroactively validated; only new keystrokes and paste operations will follow the updated rules.