Regular Expression

Flags:

Test String

Matches

How to Use the Regex Tester & Examples

This tool allows you to test JavaScript-compatible regular expressions (regex) against any text string in real-time. Matches found will be highlighted in the "Matches" area above.

Steps:

  1. Enter your regular expression pattern in the "Regular Expression" input field. Do not include the starting/ending slashes (`/`) or flags here; they are handled by the checkboxes.
  2. Select the desired flags (like `g` for global search, `i` for case-insensitive) using the checkboxes.
  3. Paste or type the text you want to test into the "Test String" area.
  4. Matches will automatically appear highlighted in the "Matches" output area as you type.
  5. If your regex pattern is invalid, an error message will be shown in the "Matches" area.

Common Flags:

  • g (Global): Find all matches rather than stopping after the first match.
  • i (Ignore Case): Makes the matching case-insensitive.
  • m (Multiline): Allows start (^) and end ($) anchors to match the start/end of lines (not just the entire string).
  • s (Dotall): Allows the dot (.) metacharacter to match newline characters (\n).
  • u (Unicode): Enables full Unicode support.
  • y (Sticky): Requires the match to occur only at the `lastIndex` position.

Example 1: Matching Email Addresses

Regex Pattern:

[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}

Flags: g | Test String:

Contact us at support@example.com or sales.info@company.co.uk. Invalid: user@localhost

Result: Highlights support@example.com and sales.info@company.co.uk.

Example 2: Extracting Hashtags

Regex Pattern:

#\w+

Flags: g | Test String:

Loving the #weekend vibes! #coding #fun

Result: Highlights #weekend, #coding, and #fun.

Example 3: Case-Insensitive Matching

Regex Pattern:

error

Flags: g, i | Test String:

An Error occurred. Please report the ERROR. No error here.

Result: Highlights Error, ERROR, and error.