> For the complete documentation index, see [llms.txt](https://docs.forms.md/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.forms.md/input-types/tel-input.md).

# Telephone input

<figure><img src="/files/rfvYfAT1uALSFeot6Eof" alt=""><figcaption><p>Telephone input</p></figcaption></figure>

Use the `telInput()` function to create telephone inputs in your forms. It uses the HTML `<input type="tel">` element which provides built-in telephone format validation.

***

## Basic usage

```javascript
import { Composer } from "formsmd";

const composer = new Composer({
  id: "my-form"
});

composer.telInput("phone", {
  question: "What is your phone number?"
});
```

Generates the following Markdown-like syntax:

```
#! id = my-form

phone = TelInput(
  | question = What is your phone number?
)
```

### Required

Add the `required` parameter to make the field mandatory:

```javascript
composer.telInput("phone", {
  question: "What is your phone number?",
  required: true
});
```

Generates the following Markdown-like syntax:

```
phone* = TelInput(
  | question = What is your phone number?
)
```

***

## Function overview

The following is the overview of the function:

```typescript
telInput(name: string, params: object)
```

### Arguments

| Name     | Type     | Description                                                                                                                                                          |
| -------- | -------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `name`   | `string` | A unique name for your form field that you'll use to identify the user's response.<mark style="color:red;">\*</mark>                                                 |
| `params` | `object` | An object containing all the configuration parameters for your telephone input field (see the [parameters section](#parameters) below for the full list of options). |

{% hint style="danger" %} <mark style="color:red;">\*</mark>Avoid values for the `name` argument which may be the names of HTML attributes, such as `"name"`, `"role"`, `"id"`, etc. This is because by default, the form's template string is first sanitized using [DOMPurify](https://github.com/cure53/DOMPurify), and these values may be removed to prevent DOM clobbering.
{% endhint %}

***

## Parameters

### Shared parameters

These parameters are common to all form fields:

| Name                  | Type                                            | Description                                                                                                                                                                                                                                                                             |
| --------------------- | ----------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `question` (required) | `string`                                        | The main question or label of the form field.                                                                                                                                                                                                                                           |
| `required`            | `true` (`boolean`)                              | When set, the field becomes required.                                                                                                                                                                                                                                                   |
| `description`         | `string`                                        | Any extra information that the user may need to fill out the form. Appears right below the question.                                                                                                                                                                                    |
| `fieldSize`           | `"sm"`                                          | When set to `"sm"`, the font sizes of the question, description, and answer are made smaller.                                                                                                                                                                                           |
| `labelStyle`          | `"classic"`                                     | When set to `"classic"`, the question and description of the form field are made smaller.                                                                                                                                                                                               |
| `subfield`            | `true` (`boolean`)                              | When set, the question and description of the form field are made smaller. Functionally the same as setting `labelStyle` to `"classic"`.                                                                                                                                                |
| `disabled`            | `true` (`boolean`)                              | When set, the input is disabled.                                                                                                                                                                                                                                                        |
| `autofocus`           | `true` (`boolean`)                              | When set, the input will be automatically focused when the parent slide becomes active, or immediately after page load.                                                                                                                                                                 |
| `id`                  | `string`                                        | The `id` attribute of the form field container.                                                                                                                                                                                                                                         |
| `classNames`          | `string[]`                                      | The CSS class names of the form field. [See the available CSS utility classes](/content/css-utility-classes.md).                                                                                                                                                                        |
| `attrs`               | `Array<{ name: string, value: string }>`        | Other HTML attributes of the form field. Each attribute has a `name` and `value` property.                                                                                                                                                                                              |
| `displayCondition`    | `{ dependencies: string[], condition: string }` | Controls when the field is shown. The `dependencies` lists the fields to watch, and `condition` is the expression that must be true to show the field. The `condition` must be a valid [Nunjucks](https://mozilla.github.io/nunjucks/) expression. [See example](#conditional-display). |

### Telephone input specific parameters

| Name                 | Type       | Description                                                                                                           |
| -------------------- | ---------- | --------------------------------------------------------------------------------------------------------------------- |
| `placeholder`        | `string`   | Sets the `placeholder` attribute of the input.                                                                        |
| `maxlength`          | `number`   | If set, this becomes the maximum number of allowed characters in the input.                                           |
| `pattern`            | `string`   | If set, the input value must match the given pattern.                                                                 |
| `value`              | `string`   | If set, this becomes the default value of the input.                                                                  |
| `country`            | `string`   | The default country code (e.g., `"US"`, `"CA"`, `"GB"`, etc. Defaults to `"US"` if not specified. ISO alpha-2 format. |
| `availableCountries` | `string[]` | Array of available country codes (e.g., `["US", "CA", "GB"]`).                                                        |

***

## Examples

### Telephone input with custom placeholder

```javascript
composer.telInput("contactPhone", {
  question: "What's your phone number?",
  description: "We'll use this number to contact you if needed",
  placeholder: "(555) 123-4567",
  required: true
});
```

Generates the following Markdown-like syntax:

```
contactPhone* = TelInput(
  | question = What's your phone number?
  | description = We'll use this number to contact you if needed
  | placeholder = (555) 123-4567
)
```

### Telephone input with specific country and available countries

```javascript
composer.telInput("phoneNumber", {
  question: "Phone number",
  description: "Please provide a UK phone number",
  country: "GB",
  availableCountries: ["GB", "IE"],
  required: true
});
```

Generates the following Markdown-like syntax:

```
phoneNumber* = TelInput(
  | question = Phone number
  | description = Please provide a UK phone number
  | country = GB
  | availableCountries = GB, IE
)
```

### Styled telephone input with custom attributes

Add CSS classes and other HTML attributes using the `classNames` and `attrs` parameters. Please note, these class names and attributes are added to the `<div>` or `<fieldset>` container that contains the actual input field(s).

```javascript
composer.telInput("phoneNumber", {
  question: "Phone number",
  classNames: ["col-6", "xs:col-6"],
  attrs: [
    { name: "style", value: "font-size: 18px;" }
  ]
});
```

Generates the following Markdown-like syntax:

```
[.col-6 .xs:col-6 style="font-size: 18px;"]
phoneNumber = TelInput(
  | question = Phone number
)
```

Please [see the available CSS utility classes](/content/css-utility-classes.md).

### Conditional display

Conditionally show or hide a telephone input field using the `displayCondition` parameter. It works as follows:

* `dependencies` lists the fields to watch.
* `condition` is the expression that must be true to show the field. This must be a valid [Nunjucks](https://mozilla.github.io/nunjucks/) expression.

For instance, in the example below, the mobile phone input will only show up if the user indicates they want to receive SMS notifications.

```javascript
composer.choiceInput("wantSMS", {
  question: "Would you like to receive SMS notifications?",
  required: true,
  choices: ["Yes", "No"]
})

composer.telInput("mobilePhone", {
  question: "Mobile phone number",
  displayCondition: {
    dependencies: ["wantSMS"],
    condition: "wantSMS == 'Yes'"
  }
});
```

Generates the following Markdown-like syntax:

```
wantSMS* = ChoiceInput(
  | question = Would you like to receive SMS notifications?
  | choices = Yes, No
)

::: [{$ wantSMS $}]
{% if wantSMS == "Yes" %}
mobilePhone = TelInput(
  | question = Mobile phone number
)
{% endif %}
:::
```

## Notes

* The selected country code is sent separately from the actual phone number during form submission. For example, if we had an input with the name `contactNumber`, the actual number would be sent under the `contactNumber` key, while the selected country code would be sent under the `contactNumberCountryCode`.