Regex Tester

Overview

Tests, evaluates, and debugs JavaScript regular expressions in real time with syntax highlighting, flag toggles, and capture group breakdowns.

Formula & Calculation Method

Matches = RegExp(Pattern, Flags).exec(Target_Text)

Evaluates search patterns with standard PCRE / ECMAScript flags: global (g), case-insensitive (i), multiline (m), dotAll (s), and unicode (u).

Worked Example: Email Validation Regex Pattern

Inputs: Pattern: /^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$/ | Target: 'user@example.com'

• Evaluate username character classes before the @ symbol.
• Validate domain host and subdomains.
• Validate top-level domain suffix (minimum 2 characters).
• Result: Match found (Valid email format).

Summary: Pattern Validated | 1 Full Match Found | Zero Syntax Errors

Common Use Cases

• Form Input Validation: Test regex rules for validating phone numbers, zip codes, passwords, and email addresses.
• Log Scraping: Extract timestamp patterns, IP addresses, and HTTP status codes from web server log files.
• Search & Replace Workflows: Formulate capture group replacement strings ($1, $2) for code refactoring.

Frequently Asked Questions

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