When a user enters invalid data, browsers automatically display validation messages.
These messages help users understand what needs to be corrected before submitting a form.
How Browser Validation Works
HTML inputs with validation rules trigger built-in browser checks.
If a rule fails, the browser prevents submission and shows a message.
If the user clicks submit without entering a name, the browser shows a message like:
“Please fill out this field.”
Validation Messages for Format Errors
Browsers also show messages when the format is incorrect.
If the user enters an invalid email, the browser displays a message like:
“Please enter an email address.”
Using the title Attribute for Custom Guidance
The title attribute provides a custom hint when validation fails.
When validation fails, the browser shows this custom message to guide the user.
Limitations of Built-in Messages
Browser validation messages:
- Cannot be fully styled with CSS
- Vary from browser to browser
When to Use Built-in Validation
Built-in validation is best for:
- Simple forms
- Quick feedback
- Reducing development time
Why Validation Messages Matter for Jobs
Good validation messages improve user experience.
Employers expect developers to understand both default and custom validation behavior.
Practice Task
Create a form with:
- A required field
- An email field
- A phone number field using pattern and title
Test how the browser displays messages.
What You Will Learn Next
In the next lesson, you will learn the difference between client-side and server-side validation.