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Syntax Explainer

JS Engine

Regex Tester & Explainer

Build, test, debug, and understand regular expressions with live match highlighting, group inspection, and step-by-step syntax explanations.

100% In-Browser • Private & Free

Regex Tester & Explainer

ECMAScript / JS Engine

Test regular expressions, inspect matches and capture groups, and understand pattern syntax in real-time.

100% Client-side. Your regular expressions and test strings are processed locally in your browser.

Preset Library

Regular Expression

//g

Flags:

Test String

141 characters • 4 lines18 words

Match Highlighting

3 matches

(0.1 ms)

1/3

Deployment schedule: - Sprint 42 Release: 2026-03-15 (Production) - Security Hotfix: 2026-04-01 (Staging) - Next Major: 2026-11-20 (Internal)

Click any highlighted match to inspect capture groups

Match Details: Match #1 of 3

Range:

[42 - 52]

Location:

Line 2, Col 22

Full Match ($&)

2026-03-15

Capture Groups

Group $1

2026

Group $2

Group $3

$<year>

2026

$<month>

$<day>

Pattern Explanation & Breakdown

23 components analyzed

Token	Type	Description & Behavior
(?<year>	group	Named capturing group "year": Captures matched content accessible under group "year"
\d	class	Digit: Matches any decimal digit [0-9]
{4}	quantifier	Quantifier: Exactly 4 times
)	group	End of group
-	literal	Literal character: Matches "-" exactly
(?<month>	group	Named capturing group "month": Captures matched content accessible under group "month"
0	literal	Literal character: Matches "0" exactly
[1-9]	class	Character set: Matches any character enclosed in "1-9"
\|	alternation	Alternation (OR): Matches either the expression before or after the pipe
1	literal	Literal character: Matches "1" exactly
[0-2]	class	Character set: Matches any character enclosed in "0-2"
)	group	End of group
-	literal	Literal character: Matches "-" exactly
(?<day>	group	Named capturing group "day": Captures matched content accessible under group "day"
0	literal	Literal character: Matches "0" exactly
[1-9]	class	Character set: Matches any character enclosed in "1-9"
\|	alternation	Alternation (OR): Matches either the expression before or after the pipe
[12]	class	Character set: Matches any character enclosed in "12"
\d	class	Digit: Matches any decimal digit [0-9]
\|	alternation	Alternation (OR): Matches either the expression before or after the pipe
3	literal	Literal character: Matches "3" exactly
[01]	class	Character set: Matches any character enclosed in "01"
)	group	End of group

Replacement Playground

Replacement Pattern

Insert tokens:

Transformed Output3 substitutions made

Deployment schedule: - Sprint 42 Release: 03/15/2026 (Production) - Security Hotfix: 04/01/2026 (Staging) - Next Major: 11/20/2026 (Internal)

Code Generator

// JavaScript Regex Match Example
const pattern = /(?<year>\d{4})-(?<month>0[1-9]|1[0-2])-(?<day>0[1-9]|[12]\d|3[01])/g;
const text = "Sample text to test against";

// Check if matches
const isMatch = pattern.test(text);
console.log("Matches:", isMatch);

// Extract all matches
const matches = [...text.matchAll(pattern)];
matches.forEach((match, index) => {
  console.log(`Match ${index + 1}: ${match[0]} at index ${match.index}`);
  if (match.groups) {
    console.log("Named groups:", match.groups);
  }
});

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Regex Tester & Explainer

Regex Tester & Explainer

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