Developer Guides
Regex for Beginners: 15 Patterns You'll Actually Use
The handful of regex building blocks you need, 15 tested patterns for everyday validation, searching and cleanup, and the mistakes that trip up beginners.
Posts tagged “Validation”
Security & Privacy
How Credit Card Numbers Work: The Luhn Algorithm
Card numbers carry their own typo check. Here's how the Luhn algorithm works step by step, what the leading digits mean, and what a passing check can't tell you.