> 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/file-input.md).
# File input
File input
Use the `fileInput()` function to create file upload inputs in your forms. It uses the HTML `` element which allows users to upload files from their device.
***
## Basic usage
```javascript
import { Composer } from "formsmd";
const composer = new Composer({
id: "my-form"
});
composer.fileInput("document", {
question: "Upload your document"
});
```
Generates the following Markdown-like syntax:
```
#! id = my-form
document = FileInput(
| question = Upload your document
)
```
### Required
Add the `required` parameter to make the field mandatory:
```javascript
composer.fileInput("document", {
question: "Upload your document",
required: true
});
```
Generates the following Markdown-like syntax:
```
document* = FileInput(
| question = Upload your document
)
```
***
## Function overview
The following is the overview of the function:
```typescript
fileInput(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.\* |
| `params` | `object` | An object containing all the configuration parameters for your file input field (see the [parameters section](#parameters) below for the full list of options). |
{% hint style="danger" %} \*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). |
### File input specific parameters
| Name | Type | Description |
| ------------- | -------- | ---------------------------------------------------------------------------------------------------------------------------- |
| `sizeLimit` | `number` | Maximum file size in MB. Defaults to `10`. Client-side check only, make sure to also validate on the server. |
| `imageOnly` | `true` | When set, only image files are accepted. Client-side check only, make sure to also validate on the server. |
| `currentFile` | `string` | The current file that exists in the database. Use a URL for best results, for example, `"https://example.s3.com/image.png"`. |
***
## Examples
### File input with size limit
```javascript
composer.fileInput("resume", {
question: "Upload your resume",
description: "PDF format preferred",
sizeLimit: 5,
required: true
});
```
Generates the following Markdown-like syntax:
```
resume* = FileInput(
| question = Upload your resume
| description = PDF format preferred
| sizelimit = 5
)
```
### Image-only file input
```javascript
composer.fileInput("profilePicture", {
question: "Profile picture",
description: "Upload a clear photo of yourself",
imageOnly: true,
sizeLimit: 2,
required: true
});
```
Generates the following Markdown-like syntax:
```
profilePicture* = FileInput(
| question = Profile picture
| description = Upload a clear photo of yourself
| imageonly
| sizelimit = 2
)
```
### File input with existing file
```javascript
composer.fileInput("document", {
question: "Update your document",
currentFile: "https://example.s3.com/previous-doc.pdf"
});
```
Generates the following Markdown-like syntax:
```
document = FileInput(
| question = Update your document
| currentfile = https://example.s3.com/previous-doc.pdf
)
```
### Styled file 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 `