Validating html file
Validation is a very common task in web applications. Data also needs to be validated before it is written into a database or passed to a web service.Symfony ships with a Validator component that makes this task easy and transparent.This interface shows errors displayed inline alongside the HTML source of the page.The interface is an interactive editor: changes to the html source result in interactive revalidation.The AMP Validator comes bundled with the AMP JS library, so it is available on every AMP page out of the box.
Given a value, a constraint will tell you if that value adheres to the rules of the constraint.
This tool checks single HTML pages for conformance with accessibility standards to ensure the content can be accessed by everyone.
See the Handbook link to the upper right for more about the Web Accessibility Checker.
Each field in the form can have zero one or more validations. More info & downloads where Do My Validation One() and Do My Validation Two() are custom functions for validation.
For example, you can have an input field that should not be empty, should be less than 25 chars and should be alpha-numeric. In some dynamically programmed pages, it may be required to change the validations in the form at run time.