Form Validation
Implement comprehensive validation rules to ensure data quality, prevent errors, and guide users to submit correct information.
Why Validation Matters
Form validation ensures data quality, prevents submission errors, and guides users to provide correct information before submitting. Good validation improves user experience and reduces support requests.
Data Integrity
Ensure only valid data enters your system
User Guidance
Help users fix mistakes before submission
Fewer Errors
Catch issues early, reduce support load
Validation Types
1. Required Fields
Mark fields as mandatory to ensure critical information is collected:
* Required field
This field is required
Please enter your full name to continue
2. Format Validation
Ensure data matches expected patterns (email, phone, URL, etc.):
Email Validation
user@example.cominvalid@emailMissing domain extensionPhone Validation
(555) 123-4567123-456Too shortURL Validation
https://example.comnot-a-urlInvalid URL format3. Length Validation
Set minimum and maximum character limits:
Please provide at least 10 characters
Length meets requirements
4. Number Range Validation
Ensure numeric values fall within acceptable ranges:
Quantity Selection
Must be at least 1
Cannot exceed 100
5. Custom Pattern Validation (Regex)
Use regular expressions for complex validation rules:
Common Regex Patterns
^\d{5}(-\d{4})?$^[A-Z]{3}-\d{4}$^4\d{15}$^[a-zA-Z0-9]+$6. File Upload Validation
Control allowed file types and sizes:
File Upload Restrictions
Drag & drop or click to upload
PNG, JPG, PDF up to 10MB
Validation Timing
Choose when validation occurs:
On Blur
Validate when user leaves the field
On Submit
Validate when form is submitted
Real-time
Validate as user types
Error Message Best Practices
Good vs Bad Error Messages
Too vague, doesn't help user fix the issue
Specific, includes example
No information about the problem
Tells user exactly what's wrong and how to fix it
Conditional Validation
Apply validation rules based on other field values:
Example: Shipping Address
Conditional Rule:
IF "Ship to different address" is checked
THEN "Shipping Address" field becomes required
Best Practices
💡 Validation Tips
Combine with Multi-Step Forms
Validate each step before allowing progression
Learn Step-by-Step Forms →