The file input uses HTML's native file input. It allows users to select files from their device for upload. In addition to native input features, it adds support for:

  • Drag and drop
  • Clearing the input
  • Repopulating from an array

Basic example

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Array value

The value of the file type should always be an array of objects where each object contains a name (string) and optional file (File) property. When selecting new files from a user’s device, FormKit will convert the native FileList to the required array-based structure automatically.

This structure can be used to pre-populate a file input with previously uploaded file values:

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Display only

Pre-populating an input with file names is for display purposes only. It’s an optional feature that provides a consistent interface to convey that a file was previously uploaded — however — a FileList is not attached to the actual <input> tag for upload.

Uploading files

The file upload process is left to your form’s submission handler. When submitting the form via full page request no further processing is necessary, however when submitting via XHR/Fetch request you will need to create an instance of FormData with the files attached. Here is a working example:

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Props & Attributes

The file input has a few unique props. There are also several commonly used native HTML attributes that assist in controlling file uploads.

Commonly used native attributes
accept----View on MDN
capture----View on MDN
multiple----View on MDN
webkitdirectory----View on MDN
file-item-iconString’’Specifies an icon to put in the fileItemIcon section. Only shows when there is a file selected. Defaults to the fileDoc icon.
file-remove-iconString’’Specifies an icon to put in the fileRemoveIcon section. Only shows when a file is selected. Defaults to the close icon.
no-files-iconString’’Specifies an icon to put in the noFilesIcon section. Only shows when no file is selected. Defaults to the fileDoc icon.
Show Universal props
configObject{}Configuration options to provide to the input’s node and any descendent node of this input.
delayNumber20Number of milliseconds to debounce an input’s value before the commit hook is dispatched.
dirtyBehaviorstringtouchedDetermines how the "dirty" flag of this input is set. Can be set to touched or comparetouched (the default) is more performant, but will not detect when the form is once again matching its initial state.
errorsArray[]Array of strings to show as error messages on this field.
helpString''Text for help text associated with the input.
idStringinput_{n}The unique id of the input. Providing an id also allows the input’s node to be globally accessed.
ignoreBooleanfalsePrevents an input from being included in any parent (group, list, form etc). Useful when using inputs for UI instead of actual values.
indexNumberundefinedAllows an input to be inserted at the given index if the parent is a list. If the input’s value is undefined, it inherits the value from that index position. If it has a value it inserts it into the lists’s values at the given index.
labelString''Text for the label element associated with the input.
nameStringinput_{n}The name of the input as identified in the data object. This should be unique within a group of fields.
parentFormKitNodecontextualBy default the parent is a wrapping group, list or form — but this props allows explicit assignment of the parent node.
prefix-iconString''Specifies an icon to put in the prefixIcon section.
preservebooleanfalsePreserves the value of the input on a parent group, list, or form when the input unmounts.
preserve-errorsbooleanfalseBy default errors set on inputs using setErrors are automatically cleared on input, setting this prop to true maintains the error until it is explicitly cleared.
sections-schemaObject{}An object of section keys and schema partial values, where each schema partial is applied to the respective section.
suffix-iconString''Specifies an icon to put in the suffixIcon section.
typeStringtextThe type of input to render from the library.
validationString, Array[]The validation rules to be applied to the input.
validation-visibilityStringblurDetermines when to show an input's failing validation rules. Valid values are blur, dirty, and live.
validation-labelString{label prop}Determines what label to use in validation error messages, by default it uses the label prop if available, otherwise it uses the name prop.
validation-rulesObject{}Additional custom validation rules to make available to the validation prop.
valueAnyundefinedSeeds the initial value of an input and/or its children. Not reactive. Can seed entire groups (forms) and lists..


You can target a specific section of an input using that section's "key", allowing you to modify that section's classes, HTML (via :sections-schema, or content (via slots)). Read more about sections here.

Single file diagram

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Multiple file diagram

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fileListA wrapper for the whole list of files.
fileItemIconAn element containing an optional fileItem icon.
fileItemAn element containing the fileName and remove action for each file.
fileNameThe element containing the name of a file.
fileRemoveThe element that removes a file from the list.
fileRemoveIconAn element containing the fileRemove icon.
noFilesThe element shown when there are no files selected.
noFilesIconAn element containing an icon within the noFiles section.
Show Universal section keys
outerThe outermost wrapping element.
wrapperA wrapper around the label and input.
labelThe label of the input.
prefixHas no output by default, but allows content directly before an input element.
prefixIconAn element for outputting an icon before the prefix section.
innerA wrapper around the actual input element.
suffixHas no output by default, but allows content directly after an input element.
suffixIconAn element for outputting an icon after the suffix section.
inputThe input element itself.
helpThe element containing help text.
messagesA wrapper around all the messages.
messageThe element (or many elements) containing a message — most often validation and error messages.


All FormKit inputs are designed with the following accessibility considerations in mind. Help us continually improve accessibility for all by filing accessibility issues here:

Semantic markupAria attributesKeyboard accessibleFocus indicatorsColor contrast with the provided themeAccessible labels, help text, and errors
Section KeyAttributeDefaultDescription
labellabelforAssociates the label to an input element. Users can click on the label to focus the input or to toggle between states.
inputinputdisabledDisables an HTML element, preventing user interaction and signaling a non-interactive state.
aria-describedbyAssociates an element with a description, aiding screen readers.
aria-requiredAdds this attribute when validation is required.
iconiconforWhenever icon is defined as a label it links it to an input element.

Keyboard Interactions

Keyboard EventDescription
TabMoves the focus to the next focusable input on the page.
Shift + TabMoves the focus to the previous focusable input on the page.