Regex Tester for JavaScript

JavaScript regex has its own quirks: no lookbehind in older engines, different flag support, and string escaping rules that trip up even experienced developers. This tester runs your patterns through the actual JavaScript RegExp engine in your browser, so what you see here is exactly what your code will produce. Test patterns with the g, i, m, s, and u flags, see all match groups, and catch edge cases before they become bugs in production.