Form Validation

MediumDOM ManipulationFormsPRO

Validate a form field by trimming input text, showing a DOM error message, and only accepting meaningful values. This exercise checks visible feedback, invalid state, and clearing errors after a valid submit.

What you'll practice

Validate a form field by trimming input text
Showing a DOM error message
Only accepting meaningful values
This exercise checks visible feedback
Invalid state
Clearing errors after a valid submit

Unlock full access

Choose a plan and go straight to secure checkout.

All 600+ interactive exercises
Full course curriculum
Access to guided projects
All future content included

Secure checkout with Stripe. Cancel anytime.