Test JavaScript regex patterns the same way they'll run in your code - using the browser's actual RegExp engine. Supports all ES2020+ flags (g, i, m, s, u, y), named capture groups, lookbehind assertions, and Unicode property escapes. Paste your pattern, paste your test string, see live matches.
When to use this
Use when: writing regex for React / Node.js / Express / Next.js code, validating form inputs in JavaScript, parsing API responses with non-trivial string patterns, building search-and-replace logic, debugging existing regex that 'sometimes works'.
Frequently Asked Questions
Is JS regex the same as PCRE / Python regex?
Mostly but not exactly. JS regex is based on the ECMAScript spec. PCRE (Perl-compatible) and Python's re module support extra features like recursive patterns, atomic groups, and possessive quantifiers that JS lacks. If you copy a regex from a Python or PHP example, double-check it works in JS first.
What's the 's' flag and when do I need it?
's' (dotAll) makes `.` match newlines. Without 's', `.` matches everything except `\n`. Added in ES2018. Use when your input is multi-line and you want to match across lines (e.g. extracting blocks of text spanning newlines).
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