About

Mass text editing requires precision to avoid data corruption or unintended context shifts. A standard global replacement often fails when dealing with homonyms or variable formatting. For instance, replacing a variable name in code without checking boundaries might break the syntax. This workspace addresses the critical need for controlled text manipulation. It integrates Regular Expressions for pattern-based search and offers a verification layer. Users can audit matches individually before commitment. This prevents the classic "Scunthorpe problem" where broad filters inadvertently modify valid substrings.

Formulas

The core logic relies on pattern matching algorithms. In JavaScript (ECMAScript), Regular Expressions are objects that match patterns with character combinations. When the global flag g is active, the engine searches for all occurrences rather than stopping after the first match.

{

MATCH if RegExp(pattern).test(str) ≡ TRUENULL otherwise

During a replacement operation with capturing groups, the string reconstruction can be visualized as mapping input segments to a new format using variables $1, $2, etc., representing the captured sub-expressions.

Reference Data

Token	Description	Example Pattern	Matches Example
.	Any single character (except newline)	a.c	abc, a@c, a c
^	Start of string/line	^Hello	Hello World
$	End of string/line	end$	The end
*	Zero or more repetitions	ab*c	ac, abc, abbc
+	One or more repetitions	ab+c	abc, abbc
?	Zero or one repetition	colou?r	color, colour
\d	Any digit	user_\d+	user_12, user_007
\w	Word character (alphanumeric + underscore)	\w{3}	Car, 123, _id
\s	Whitespace character	key\sval	key val, key val
[]	Character Set	[aeiou]	a, e, i, o, u
[^]	Negated Set	[^0-9]	a, B, $ (No digits)
()	Capturing Group	(abc)	abc (Groups it)
\|	Alternation (OR)	cat\|dog	cat, dog
\	Escape special character	\$100	$100

Frequently Asked Questions

This usually happens due to "greedy" quantifiers like * or +. By default, these tokens match as much text as possible. You can make them "lazy" (matching as little as possible) by adding a question mark after the quantifier, such as *? or +?.

Standard Regex does not inherently support intelligent case preservation (converting "Apple" to "Banana" and "apple" to "banana" automatically). You must either perform two separate passes or use a custom replacement function logic, which this tool's "Step-by-Step" mode simulates by allowing manual verification.

The tool validates the Regular Expression syntax before execution. If the syntax is incorrect (e.g., unmatched parentheses or invalid escape sequences), the system will flag the error and prevent execution to ensure the browser does not freeze.

Yes. If you define capturing groups in your Find pattern using parentheses, you can reference them in the Replace field using $1, $2, etc. For example, finding "(\w+) (\w+)" and replacing with "$2, $1" swaps two words.

Yes. You can enable the "Multi-line" flag. This changes the behavior of the start (^) and end ($) anchors to match the start and end of each line, rather than just the start and end of the entire string.