NovIqraLab

Regex Tester & Debugger

Test, debug, and validate JavaScript regular expressions in real-time with visual pattern matching, flags selection, and group breakdown.

Common Patterns:
/ /
0 Matches Found
Captured Groups & Index Details:
Match # Full Match Start/End Index Captured Groups
No matches evaluated yet.

What is Regular Expression (Regex) Testing?

A Regular Expression (Regex) is a powerful sequence of characters defining a search pattern. Developers use Regex across languages like JavaScript, C#, Python, and Java for data extraction, string replacement, input validation, and lexical parsing.

This interactive tester parses your pattern on-the-fly, displaying matched substrings with visual highlight overlays and extracting sub-captures so you can verify logic before adding code to production.

Regex Quick Cheat Sheet

Syntax Symbol Meaning & Function Example Match
\d / \D Matches any digit (0-9) / Non-digit character. \d+ matches 1024
\w / \W Matches any word character (alphanumeric + underscore) / Non-word. \w+ matches user_name
[a-z] Character set class - matches any character within specified range. [A-Z] matches capital letters
+ / * / ? Quantifiers: 1 or more / 0 or more / 0 or 1 (optional). a+ matches a, aa
^ / $ Anchors: Start of line / End of line. ^https matches URLs starting with https
( ... ) Capturing Group - extracts matched portion into array index. (\d{3}) captures area codes

How to use Regex Tester & Debugger

  1. Enter or paste the values requested in the input fields.
  2. Choose any options provided, then run an action button if the tool requires one.
  3. Review the result and copy or adjust it as needed.

Regex Tester & Debugger features

  • Available tool controls: Email, URL, Phone.
  • Input and option fields: Regular Expression & Flags:, g, i.

Frequently Asked Questions (FAQ)

This engine uses native ECMAScript (JavaScript) RegExp mechanics directly within your browser. Patterns work seamlessly for client-side JavaScript, Node.js, and modern browser scripts.

g (Global): Finds all occurrences rather than stopping after the first match.
i (Case Insensitive): Ignores capital/lowercase letter differences.
m (Multiline): Makes ^ and $ match start/end of individual lines.
s (DotAll): Allows . to match newline characters.

No. All evaluation, highlighters, and group extractions execute completely locally inside your browser context.