Online regex tester and debugger with real-time match highlighting, detailed explanations, substitutions, unit tests, benchmarking, and code generation. Support
Joined December 2011
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TIL V8 can keep huge strings alive through legacy RegExp last-match state.
In short, a regex match can keep the entire input string alive -- even after you’re done using it. It stays allocated, adding unnecessary memory pressure, until another successful match replaces that state.
Since everybody loves regex so much, I’ve remade the regex quiz on the site from scratch. New and improved challenges, try it on regex101.com/quiz
Have you considered regex101 Pro but decided not to subscribe? What held you back? I’d love to hear what I could improve.
I saw this great library submission recently, and just wanted to take the opportunity to give kudos to its author, Tiago Cussiol, and share it with you all.
Super detailed description, and a 560 unit test suite to back it up: regex101.com/library/0BFrkM
Try it on regex101.com or checkout the docs: docs.regex101.com/applicatio…
You can now convert regexes between flavors directly on regex101!
Write your regex in the flavor you know best, then convert it with confidence to the flavor you need. 🔄
How do you prefer to read the changelog? Should I try to categorize it, or just keep the numbered list?
There are two "ana"s in "banana". 🍌
/ana/g only finds one.
/(?=(ana))/g captures both.
The trick: a lookahead checks ahead without consuming characters, so overlapping captures are possible.
#regex #JavaScript
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