2025-12-12 1 min read
Enforcing Password Complexity with Lookaheads
Don't chain five separate if-statements. Use a single regex with positive lookaheads to enforce password rules like length, digits, and special characters.
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Regex Mastery
Tutorials & Guides
Actionable regular expression tutorials, debugging playbooks, and production-ready patterns.
2025-12-10 1 min read
Robust URL Validation Regex
Matching URLs is harder than it looks. We explore patterns for matching HTTP/HTTPS, domains, ipv4, and optional paths.
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2025-12-08 1 min read
Optimizing Performance: Avoiding Catastrophic Backtracking
Regular expressions can crash servers. Learn how to identify and fix performance bottlenecks, specifically the dreaded Catastrophic Backtracking.
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2025-12-07 1 min read
Greedy vs Lazy Quantifiers: A Visual Guide
Why does your regex match too much? Understanding the difference between greedy (*) and lazy (*?) quantifiers is the first step to mastery.
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2025-12-05 1 min read
Python vs JavaScript Regex: Key Differences You Must Know
Switching between Python and JS? A comprehensive comparison of the 're' module vs the native RegExp object to save you from syntax errors.
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2025-12-03 1 min read
Mastering Lookbehind Assertions in JavaScript (ES2018)
JavaScript (ES2018) finally introduced lookbehind assertions. Discover how to use them to match text purely based on what comes before it.
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Upcoming Pattern Posts
Editorial roadmap for new pattern-focused guides. We publish these as hands-on tutorials with runnable examples.
- Planned
Regex Patterns for Financial Identifiers (IBAN, SWIFT, Routing)
Focus: Validation
- Drafting
Regex Patterns for Analytics Events and Naming Conventions
Focus: Data
- Planned
Regex Patterns for File and Path Security Hardening
Focus: Security