# Number input

<figure><img src="/files/yhzVhvplcDDdocTZenSv" alt=""><figcaption><p>Number input</p></figcaption></figure>

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

***

## Basic usage

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

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

composer.numberInput("quantity", {
  question: "How many items would you like?"
});
```

Generates the following Markdown-like syntax:

```
#! id = my-form

quantity = NumberInput(
  | question = How many items would you like?
)
```

### Required

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

```javascript
composer.numberInput("quantity", {
  question: "How many items would you like?",
  required: true
});
```

Generates the following Markdown-like syntax:

```
quantity* = NumberInput(
  | question = How many items would you like?
)
```

***

## Function overview

The following is the overview of the function:

```typescript
numberInput(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 number 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). |

### Number input specific parameters

| Name          | Type     | Description                                                                         |
| ------------- | -------- | ----------------------------------------------------------------------------------- |
| `placeholder` | `string` | Sets the `placeholder` attribute of the input.                                      |
| `min`         | `number` | Sets the minimum allowed value.                                                     |
| `max`         | `number` | Sets the maximum allowed value.                                                     |
| `step`        | `number` | Sets the stepping interval.                                                         |
| `unit`        | `string` | Text to display before the input as a unit (e.g., `"$"`, `"€"`). Purely decorative. |
| `unitEnd`     | `string` | Text to display after the input as a unit (e.g., `"kg"`, `"%"`). Purely decorative. |
| `value`       | `number` | If set, this becomes the default value of the input.                                |

***

## Examples

### Number input with range limits

```javascript
composer.numberInput("age", {
  question: "What is your age?",
  description: "Must be 18 or older to participate",
  min: 18,
  max: 120,
  required: true
});
```

Generates the following Markdown-like syntax:

```
age* = NumberInput(
  | question = What is your age?
  | description = Must be 18 or older to participate
  | min = 18
  | max = 120
)
```

### Number input with unit

```javascript
composer.numberInput("price", {
  question: "Enter the price",
  unit: "$",
  step: 0.01,
  min: 0,
  required: true
});
```

Generates the following Markdown-like syntax:

```
price* = NumberInput(
  | question = Enter the price
  | unit = $
  | step = 0.01
  | min = 0
)
```

### Styled number 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.numberInput("quantity", {
  question: "Quantity",
  classNames: ["col-4", "xs:col-6"],
  attrs: [
    { name: "style", value: "font-size: 18px;" }
  ]
});
```

Generates the following Markdown-like syntax:

```
[.col-4 .xs:col-6 style="font-size: 18px;"]
quantity = NumberInput(
  | question = Quantity
)
```

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

### Conditional display

Conditionally show or hide a number 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 quantity field will only show up if the user wants to make a purchase.

```javascript
composer.choiceInput("wantToPurchase", {
  question: "Would you like to make a purchase?",
  required: true,
  choices: ["Yes", "No"]
})

composer.numberInput("quantity", {
  question: "How many would you like to purchase?",
  min: 1,
  displayCondition: {
    dependencies: ["wantToPurchase"],
    condition: "wantToPurchase == 'Yes'"
  }
});
```

Generates the following Markdown-like syntax:

```
wantToPurchase* = ChoiceInput(
  | question = Would you like to make a purchase?
  | choices = Yes, No
)

::: [{$ wantToPurchase $}]
{% if wantToPurchase == "Yes" %}
quantity = NumberInput(
  | question = How many would you like to purchase?
  | min = 1
)
{% endif %}
:::
```

## Notes

* The `unit` and `unitEnd` parameters are purely decorative. They have no effect on the actual value of the input sent during form submission.


---

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