different ways. Examples might be simplified to improve reading and learning. Be Smart and Future Proof. you must write JavaScript code. The step Attribute. The HTML5 form validation techniques in this post only work on the front end. The Nu HTML5 is a popular HTML 5 Validator Online tool. Tutorials, references, and examples are constantly reviewed to avoid errors, but we cannot warrant full correctness of all content. If you want to report an error, or if you want to make a suggestion, do not hesitate to send us an e-mail: