Form Validation

Validation ensures users enter correct data before submission. React allows you to validate inputs as users type or when they submit the form.

Validation Basics

There are two main approaches to validation:

Validation Functions

Create reusable validation functions for common patterns:

Form with Validation State

Combining form state with validation:

Exercise: Required Field Validator

Exercise: Email Validator

Exercise: Password Validator

Displaying Error Messages

Show errors to users in a clear way:

Touched State

Only show errors after the user has interacted with a field:

Key Takeaways

1. Two approaches - Validate on submit or on change
2. Reusable validators - Create functions for common patterns
3. Combine validators - Chain multiple checks for one field
4. Touched state - Only show errors after user interaction
5. Clear error display - Inline and summary error messages