Stimulus-form-validation - Experimental

Add inline validation to your forms with ease.

• Use any HTML5 validation such as required
• Supports custom validations
• Auto disables/enable the submit button when the form's validity status changes.

Install

yarn add stimulus-form-validation npm install stimulus-form-validation

Basic usage

Register the controller

import { Application } from "stimulus"
import FormValidationController from "stimulus-form-validation"

const application = Application.start()
application.register("validation", FormValidationController)

HTML

<div data-controller="validation">
  <form action="">
    <!-- Add a selector to the field's container -->
    <!-- We will use the default selector, but it can be configured, see later. -->
    <div data-field-container>
      <label>Name</label>
      <input type="text" required />
    </div>
    <button>Submit</button>
  </form>
</div>

CSS

.container-error {
  /* your styles for the field container */
}

.field-error {
  /* your styles for the field */
}

.error-message {
  /* your styles for the error message */
}

Custom validations

First, define your validation function. The function should return a Promise and reject with an error message if it fails validation.

function userNameAvailable(element) {
  const { value } = element

  return new Promise(async (resolve, reject) => {
    const available = await fetch(`usernameexamples.com/${value}`)

    available ? resolve() : reject("Username not available")
  })
}

Next, register the function:

import { addValidation } from "stimulus-form-validation"

addValidation("userNameAvailable", userNameAvailable)

Finaly add data-validates="userNameAvailable" to the input element

<input type="text" data-validates="userNameAvailable" required/>

The data-validates takes a space delimited method list, so feel free to add more than one validator.

Error messages

TODO

Configruation

Default configruation

{
  containerSelector: "[data-field-container]",
  errorMessageClass: "error-message",
  errorMessagePosition: "end",
  containerErrorClass: "container-error",
  fieldErrorClass: "field-error",
  debounceMs: 150,
  focusOnError: "true",
}

Option	Description	Data attribute
containerSelector	Used, by the controller, to located the field's container.	data-identifier-container-selector
errorMessageClass	class for the error message	data-identifier-error-message-class
errorMessagePosition	Where to place the error message. Accepted values are 'end' or 'start'	data-identifier-error-message-position
containerErrorClass	Class added to the container if the field has an error	data-identifier-container-message-class
fieldErrorClass	Class added to the field if the field has an error	data-identifier-field-error-class
debounceMs	Validate debounce time in ms	data-identifier-debounce-ms
focusOnError	Whether to focus the first field if there is an error on submit	data-identifier-focus-on-error

Can be overwritten via a data attribute or globaly like so:

import { config } from "stimulus-form-validation"

config({
  containerSelector: "your-selector",
})

Advance

You can fully customize how an error message is displayed by overwriting the display method. The display method receives two arguments, the element, and the error message.

import FormValidationController from "stimulus-form-validation"

export default class extends FormValidationController {
  display(element, errorMessage) {
    alert(errorMessage)
  }
}

Contributing

Bug reports and pull requests are welcome.

License

This package is available as open source under the terms of the MIT License.