JavaScript Regular Expression Tester
Test JS regex patterns with match, replace, and split operations
Regex Configuration
Operation Type
JavaScript Regex Flags
Test Results
No JavaScript regex tests performed yet
Enter a regex pattern and test text, then click "Test JavaScript Regex"
Quick JavaScript Regex Examples
Email Validation
/^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$/
Validates email addresses with proper format
Phone Number
/\d{3}-\d{3}-\d{4}/
Matches phone numbers in XXX-XXX-XXXX format
URL Pattern
/https?:\/\/[^\s]+/g
Matches HTTP and HTTPS URLs globally
Hashtag
/#\w+/g
Matches hashtags starting with #
Date Format
/\d{4}-\d{2}-\d{2}/
Matches YYYY-MM-DD date format
Strong Password
/^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[@$!%*?&])[A-Za-z\d@$!%*?&]{8,}$/
Validates strong password requirements
When to Use JavaScript Regex Tester
JavaScript Development
Test regex patterns before implementing in JavaScript applications, validate input processing, and debug pattern matching
Input Validation
Validate user inputs, sanitize data, and ensure proper format compliance in web applications and APIs
Text Processing
Extract data from text, parse log files, process documents, and perform complex text transformations
Learning & Education
Learn JavaScript regex syntax, practice pattern matching, understand JS regex features, and debug complex expressions
Debugging
Debug existing regex patterns, identify matching issues, optimize performance, and fix pattern errors
Data Extraction
Extract specific data from text, parse structured formats, and process large datasets with regex patterns
Frequently Asked Questions
What is a JavaScript regex tester?
A JavaScript regex tester is a tool that allows developers to test and validate regular expressions using JavaScript's native regex engine. It provides real-time pattern matching, replacement operations, string splitting, and debugging capabilities. This tool helps developers write, test, and debug regular expressions before implementing them in JavaScript applications, ensuring patterns work correctly with JavaScript's specific regex behavior.
How do I use this JavaScript regex tester?
Using our JavaScript regex tester is simple: 1) Enter your regular expression pattern in the regex input field, 2) Add test text in the text input area, 3) Choose operation type (Match, Replace, or Split), 4) Configure JavaScript regex flags (g, i, m, s, u, y), 5) For replace operations, enter replacement text, 6) Click 'Test Regex' to see results with match highlighting and detailed analysis.
Is this JavaScript regex tester free to use?
Yes, our JavaScript regex tester is completely free to use with no registration required. You can test unlimited regular expressions, use all features including match/replace/split operations, and access all functionality without any cost. There are no hidden fees, premium features, or usage limits.
What JavaScript regex operations are supported?
Our JavaScript regex tester supports three main operations: Match (find all matches with highlighting), Replace (replace matched text with new content), and Split (split text using regex as delimiter). All operations support JavaScript's native regex flags including global (g), case-insensitive (i), multiline (m), dotall (s), Unicode (u), and sticky (y) matching.
What are JavaScript regex flags?
JavaScript regex flags modify how patterns are matched: 'g' (global) finds all matches, 'i' (ignore case) makes matching case-insensitive, 'm' (multiline) makes ^ and $ match line boundaries, 's' (dotall) makes . match newlines, 'u' (Unicode) enables full Unicode support, and 'y' (sticky) matches only at the lastIndex position. Our tool supports all these flags with real-time configuration.
Can I test replace operations with capture groups?
Yes, our JavaScript regex tester fully supports replace operations with capture groups. You can use $1, $2, $3, etc. in your replacement text to reference captured groups, or use $& for the entire match, $` for text before the match, and $' for text after the match. The tool shows detailed group information and replacement results.
How accurate is the JavaScript regex testing?
Our JavaScript regex tester uses the browser's native JavaScript regex engine, ensuring 100% accuracy with JavaScript's regex implementation. All operations (match, replace, split) behave exactly as they would in actual JavaScript code, including flag behavior, group handling, and edge cases. This makes it perfect for testing patterns before implementing them in JavaScript applications.
Can I debug complex JavaScript regex patterns?
Yes, our JavaScript regex tester is excellent for debugging complex patterns. It provides detailed match information, group extraction, position tracking, and real-time highlighting. You can test your pattern against various inputs, see exactly what matches and what doesn't, identify performance issues, and refine your regex until it works perfectly. The tool is particularly useful for debugging nested groups, lookahead/lookbehind assertions, and complex character classes.
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