05 // Unicode, Symbol & Encoding WorkbenchREGEX-TESTER
Live Regular Expression (RegExp) Tester & Capture Group Inspector
Evaluates ECMAScript `RegExp` patterns in real time against multi-line sample text, tabulating every match index, full match string, and capture group.
2 MATCH(ES)
#1 @ 6: #FT-2026-0042: $1,250.00Groups: [FT-2026-0042, 1,250.00]
#2 @ 39: #FT-2026-0109: $480.50Groups: [FT-2026-0109, 480.50]
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Reference Table
- 01Enable the `u` (Unicode) flag whenever matching astral code points (`\u{1F680}`) or Unicode property escapes (`\p{Letter}`, `\p{Number}`).
- 02Avoid nested unbounded quantifiers like `(a+)+$` which can cause catastrophic backtracking (`ReDoS`) on non-matching inputs.
Frequently Asked Questions
What does the `s` (dotAll) flag do in RegExp?+
By default `.` matches any character except line terminators (`\n`, `\r`); adding flag `s` allows `.` to match newlines too.
How do named capture groups work in modern JavaScript?+
Write `(?<year>\d{4})-(?<month>\d{2})` and access `match.groups.year` directly by name.
What is a non-capturing group `(?:...)`?+
`(?:abc)+` groups tokens for quantification or alternation without allocating a numbered capture slot.