Parsley.js provides client-side form validation UX without writing JavaScript boilerplate.
Initialization
// Recommended JavaScript initialization
$('#myForm').parsley({
errorClass: 'is-invalid',
successClass: 'is-valid'
});
Standard HTML Validation Constraints
<!-- Required -->
<input required />
<!-- Email & URL Types -->
<input type="email" />
<input type="url" />
<!-- Length Limits -->
<input minlength="6" maxlength="20" />
<input data-parsley-length="[6, 20]" />
<!-- Numeric & Regex Pattern -->
<input pattern="^[A-Z0-9]+$" />
<input data-parsley-type="digits" />
<input data-parsley-type="alphanum" />
<!-- Number Range -->
<input type="number" min="1" max="100" />
<input data-parsley-range="[1, 100]" />
<!-- Checkbox Selection Bounds -->
<input type="checkbox" name="hobbies" data-parsley-mincheck="2" />
<!-- Match Password Confirmation -->
<input id="password" type="password" />
<input type="password" data-parsley-equalto="#password" />
JavaScript Form & Field API
Form Methods
const form = $('#myForm').parsley();
form.isValid(); // Returns true if valid, false if invalid
form.validate(); // Runs validation and renders error messages
form.reset(); // Resets validation state and clears errors
form.destroy(); // Unbinds Parsley handlers from form
Field Methods
const field = $('#username').parsley();
field.isValid();
field.validate(); // Returns array of failing constraint objects
Custom Validators
Register custom domain validators globally:
window.Parsley.addValidator('multipleOf', {
requirementType: 'integer',
validateNumber(value, requirement) {
return value % requirement === 0;
},
messages: {
en: 'This value must be a multiple of %s.'
}
});
Usage in markup:
<input type="number" data-parsley-multiple-of="5" />