Validation with Iodine

Client-side validation for a two-field form with Iodine and fetchit:before.

Important!

Client-side validation is not secure and should only be used to improve user experience.

Setup

CDN:

<script src="https://cdn.jsdelivr.net/npm/@caneara/iodine@8/dist/iodine.min.umd.js" defer></script>

Markup

novalidate disables built-in browser validation. For AJAX, add [data-success] and [data-validation-error] (selectors).

modx

<form action="[[~[[*id]]]]" method="post" novalidate>
  <label> Name
    <input type="text" name="name" value="[[+fi.name]]" />
    <span data-error="name">[[+fi.error.name]]</span>
  </label>
  <label> E-mail
    <input type="email" name="email" value="[[+fi.email]]" />
    <span data-error="email">[[+fi.error.email]]</span>
  </label>
  <div role="alert" data-success style="display: none;"></div>
  <div role="alert" data-validation-error style="display: none;"></div>
  <button type="submit">Submit</button>
</form>

fenom

<form action="{$_modx->resource.id | url}" method="post" novalidate>
  <label> Name
    <input type="text" name="name" value="{$_modx->getPlaceholder('fi.name')}" />
    <span data-error="name">{$_modx->getPlaceholder('fi.error.name')}</span>
  </label>
  <label> E-mail
    <input type="email" name="email" value="{$_modx->getPlaceholder('fi.email')}" />
    <span data-error="email">{$_modx->getPlaceholder('fi.error.email')}</span>
  </label>
  <div role="alert" data-success style="display: none;"></div>
  <div role="alert" data-validation-error style="display: none;"></div>
  <button type="submit">Submit</button>
</form>

Handler

Iodine.assert takes a fields object and rules. On failure, call preventDefault, then setError / clearError:

document.addEventListener('fetchit:before', (e) => {
  const { formData, fetchit } = e.detail
  const fields = Object.fromEntries(formData.entries())
  const rules = {
    name: ['required', 'minLength:5'],
    email: ['required', 'email'],
  }

  const validation = Iodine.assert(fields, rules)
  if (validation.valid) {
    return
  }

  e.preventDefault()

  for (const [name, field] of Object.entries(validation.fields)) {
    if (field.valid) {
      fetchit.clearError(name)
      continue
    }

    fetchit.setError(name, field.error)
  }
})

Keep server-side checks in FormIt (or your own snippet):

modx

[[!FetchIt?
  &form=`myForm.tpl`
  &validate=`name:required:minLength=^5^,email:required:email`
]]

fenom

{'!FetchIt' | snippet : [
  'form' => 'myForm.tpl',
  'validate' => 'name:required:minLength=^5^,email:required:email',
]}

FormIt validators: FormIt documentation.