Regex Pattern Builder

Version: 1.0 Added: Jan 21, 2026

Description

Creates and explains regular expressions for common patterns. Provides test cases, explains each component, and handles edge cases properly.

Code

Skill Code

Regex includes:
1. Pattern with explanation
2. Flags needed (g, i, m)
3. Test cases (matches and non-matches)
4. Edge cases handled
5. Performance considerations
6. Alternative patterns "keyword">if applicable

Usage Examples

Examples

User: regex to validate phone numbers

Claude: 
```javascript
// US phone: (123) 456-7890 or 123-456-7890
"keyword">const phoneRegex = /^\(?([0-9]{3})\)?[-. ]?([0-9]{3})[-. ]?([0-9]{4})$/;

// Breakdown:
// ^\(?      - Optional opening paren
// ([0-9]{3}) - Area code (captured)
// \)?       - Optional closing paren
// [-. ]?     - Optional separator
// ...

// Test cases:
// ✓ (555) 123-4567
// ✓ 555-123-4567
// ✗ 55-123-4567 (invalid area code)
```

Installation

Add the following to your CLAUDE.md file (project root or ~/.claude/CLAUDE.md for global):

CLAUDE.md

# Regex Pattern Builder

Regex includes:
1. Pattern with explanation
2. Flags needed (g, i, m)
3. Test cases (matches and non-matches)
4. Edge cases handled
5. Performance considerations
6. Alternative patterns if applicable

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