HTML5 offers form field validation support built into the HTML form input tags that should greatly reduce the need for JavaScript validation code. In this post, I look at some examples of this.

However there are valid reasons why you should consider valid HTML. Related: W3C Validator: What It Is & Why It Matters For SEO 6 Reasons Google Advises to Validate HTML 1. Could affect crawl rate 2.

Take advantage of automatic model state validation in ASP.Net Core to avoid tedious manual coding for HTML form validation ...

WordPress 5.3 will bring it closer to valid HTML. Good news to those who value standards compliant HTML.