- Client-side form validation
- Using Built-in Form Validation
- The Required Attribute
- Validating Against a Regular Expression
- Constraining the Length of Your Entries
- Full Example
- The Constraint Validation API
- Implementing a Customized Error Message
- A More Detailed Example
- Validating Forms Without a Built-in API
- Form Validation Quiz 6 questions
Quiz Question 1 of 6
Why is it important to validate data on both the client-side and the server-side?
Choose the correct answer below: