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Pattern Tool

Test JavaScript regular expressions against sample text.

Pattern Tool

Regex Tester

Test a JavaScript regular expression against sample text and review the matches without leaving the browser. Useful for quick validation and debugging.

This online regex tester is built for JavaScript-style regular expressions, so it is helpful when debugging patterns for frontend code, Node.js utilities, form validation, or log parsing.

Tool UI

Run a regex test


          

          

        

        

          
About the regex tester

          
This page helps you test JavaScript regular expressions against sample text without opening a full IDE or application runtime. It is useful for quick iteration when designing search patterns, validators, or parsing logic.

          
The goal is to make regex behavior visible quickly so you can adjust the pattern and flags with less trial and error.

        

        

          
How to test a regular expression

          
    
            
  1. Enter the regex pattern without surrounding slashes.
    2. 
            
  2. Add any JavaScript flags such as g, i, or m.
    3. 
            
  3. Paste the sample text you want to test.
    4. 
            
  4. Select Run test and review the match output.
    5. 
          

          

            This is useful for checking validation rules, extracting IDs, matching words, splitting
            logs, or confirming how a pattern behaves before shipping it into application code.
          

        

        

          
What is a regular expression?

          
A regular expression, often shortened to regex, is a pattern language used to search, validate, or extract text. Regex can match words, numbers, dates, IDs, delimiters, and many other text structures.

          
In JavaScript, regex is commonly used in forms, string processing, search features, and log or text parsing workflows.

        

        

          
Why use a regex tester?

          
Regular expressions can be difficult to reason about by inspection alone. A tester lets you experiment with patterns and flags on real text before you commit the pattern into code.

          
This reduces debugging time and helps confirm exactly what a pattern matches or misses.

        

        

          
Regex tester FAQ

          
What do regex flags do?

          
Flags change how the pattern behaves. For example, g finds all matches, i ignores case, and m changes how line anchors behave.

          
Why do I need to escape backslashes?

          
Backslashes are special in regex syntax. Depending on where a pattern comes from, you may need extra escaping when moving between code strings and a test tool.

          
What is the difference between one match and global matching?

          
Without the global flag, many JavaScript regex operations stop after the first match. With g, the engine keeps scanning for more matches.

          
Is this the same as PCRE or another regex engine?

          
No. This page is positioned around JavaScript regex behavior, so patterns that work in other engines may differ slightly here.

        

        

          
Regex tips

          
    
            
  • Test with realistic sample text, not only ideal examples.
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  • Use flags deliberately because they change matching behavior a lot.
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  • Escape special characters when you need a literal match.
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  • Check global behavior separately from first-match behavior.
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