Accessing Forms and Form Objects
Creating Dynamic Forms
Event Handling Form Submission
Form Validation API
Overview/Review | Accessing Elements | Creating Form Elements | Submission | Validation | Worksheet
If you need to review the form elements/attributes and form styling:
Web forms - Working with user data - Learn web development | MDN
Wendi's Web - HTML: Form Validation
You already know how to do some basic client-side validation for your forms, so review (up to the section on “Validating Forms using JavaScript”)