Parsley.js is a JavaScript form validation library that provides a client-side data validator for verifying input correctness before submission. It functions as an HTML attribute-based validator, allowing constraints to be defined declaratively within HTML data attributes to enforce rules without requiring custom scripts.
The framework distinguishes itself through a customizable validation system that supports user-defined rules and custom error message templates. It includes a remote validation interface to verify form values against server endpoints via asynchronous network requests and supports organized validation grouping to handle specific subsets of a form independently.
The library covers a broad range of frontend data integrity capabilities, including input whitespace cleansing and dynamic form adaptation to monitor real-time modifications to fields. It provides mechanisms for form submission interception, validation trigger configuration, and customizable error display rendering.
