Regex Cheat Sheet by Language (JS, Python, PHP, Java, Go)

Most regex syntax is universal but each language has its quirks. Python supports named groups as (?P<name>); JavaScript uses (?<name>). Go's RE2 doesn't support lookbehinds. PHP's PCRE has its own flag set. This cheat sheet lists every common regex feature with its syntax in JavaScript, Python, PHP, Java, Go, and .NET side-by-side.

How to use the Regex Cheat Sheet by Language (JS, Python, PHP, Java, Go)

Browse the full reference or filter by keyword. Each row shows the feature's syntax in each language; columns highlight where they differ.

Why a regex is not always portable

The core of regular expressions — classes, quantifiers, groups — is shared, but every language ships a different engine with its own dialect. PHP uses PCRE, JavaScript uses ECMAScript, Python has its own re module, Java has java.util.regex, .NET has its own, and Go uses RE2. They disagree on named-group syntax, lookbehind support, inline flags, and how much Unicode they assume by default.

RE2 is the sharpest example: to guarantee linear-time matching, Go deliberately drops backreferences and lookarounds, so a pattern that works in PHP can simply fail to compile in Go. This side-by-side reference lines the features up across six languages so you can spot the quirk that is about to bite before you port a pattern.

Common use cases

• Porting a pattern — translate a working regex from Python to Go or JavaScript without trial and error.
• Code review — confirm a pattern uses syntax the target language actually supports.
• Choosing a language for a job — decide whether you need lookbehind or backreferences before you start.
• Polyglot teams — keep one mental model when you switch between back-end and front-end regex.
• Learning the edge cases — see exactly where the dialects diverge instead of memorising them.