Steven Levithan

Regex+ 6.1.0 released. Adds even cleaner and more robust interpolation of RegExp instances and partial patterns. And improved docs. 😀 github.com/slevithan/re...

Oniguruma-To-ES now has 12M dl/m. Most of that comes from Shiki, which uses it to make VSCode-style syntax highlighting possible in native JS (no large WASM). I like to think it's contributing to Shiki's rapid growth :) Recent example is in Vercel's streamdown.ai

Neither @antfu.me nor I thought this was possible when we started down this road. But it's finally done 😁

Great tips

The latest version of Regex Colorizer (a project I started in 2007) is finally available via npm, after getting the package name transferred to me 😊 github.com/slevithan/re...

Thanks so much @brc-dd.dev for the generous sponsorship!! Appreciate all the great work you do for VitePress and open source!

Improved the docs for regex-recursion, highlighting standalone usage (without Regex+). Less than 2 kB for recursive regex matching with support for all ES2025 regex syntax. github.com/slevithan/re...

🚢 Released emoji-regex-xs v2.0. Now matches all underqualified emoji included in Unicode's emoji-test.txt list, to better match @mths.be's excellent emoji-regex and real-world emoji use. Lib size reduced from 0.3 to 0.2 kB in the process :)

Regular expressions should not change the length of a match based on case insensitivity. My case for a breaking change in Oniguruma: github.com/kkos/oniguru...

oniguruma-to-es v4.2.0 shipped! 🚢 Continues improving by far the most sophisticated regex translator in the world. JS coders who've never used Oniguruma might still find it useful if they want much more feature-rich regexes (with native perf!) github.com/slevithan/on...

oniguruma-parser v0.10.0 brings a bunch of quality of life improvements. 🚀 The regex optimizer it includes, which is probably the most interesting part for people who don't regularly use Oniguruma, has continued to improve! github.com/slevithan/on...

Any React Native devs, can you help me by testing whether Regex+ works at all in RN 0.75.1+ or RN 0.74.6+? 🙏🏻😌 Related issue: github.com/slevithan/re...

Migrated a bunch of tests from Jasmine to Vitest so I could use TypeScript more easily. Super nice! ⚡ Will be trying to use Vitest everywhere from now on.

Over the last week and with major help from RedCMD, we converted all of oniguruma-parser from JS to TS. 🎉 Surprised that all of this work uncovered 0 bugs (despite the high complexity of the migrated code), which I think speaks to the pre-existing high quality of the lib. github.com/slevithan/on...

Request to run VS Code's syntax highlighting grammars through my Oniguruma regex optimizer (like Shiki does), which would improve highlighting performance for some languages like C++ and reduce the size of VS Code: github.com/microsoft/vs...

Just shipped version 0.6 of oniguruma-parser, which includes a new optimization that is able to automatically identify and fix some ReDoS vulnerabilities without changing what the regex matches. It already identified one such regex in the Haskell grammar used by @shiki.style

Although it's not in the release notes, @shiki.style 3.2.0 includes slight-to-major performance improvements for many languages (for both the Oniguruma and JS engines), thanks to the new regex optimizer from `oniguruma-parser`. Worth upgrading!

Adding my new regex optimizer to @shiki.style: github.com/shikijs/text... - It shaves more than 35,000 chars off just the C++ grammar (as an example) compared to the prior minification (without any change in meaning), and makes some of its regexes significantly faster ⚡🚀

More oniguruma-parser updates! An example of what it's optimizer/minifier can do, in the image. Some transforms can significantly improve perf for complex regexes 🚀

Lots of improvements released for my new Oniguruma optimizer (minifies regexes and improves their perf), plus added a new demo page: github.com/slevithan/on...

New launch! `oniguruma-parser` extracts the parser/traverser from my Oniguruma-To-ES transpiler, makes a ton of improvements, and adds new code generator and optimizer modules: github.com/slevithan/on... Great for TextMate grammar authors and anyone who works with Oniguruma regexes

Oniguruma-To-ES v3.1.0 includes a new feature I think is new in JS: Lazy construction of RegExp objects, deferred until first use in a search (with nothing observably different before/after). Also allows lazy-compile based on pattern length, since only very long patterns are slow to construct in V8

Using Oniguruma → JavaScript regex transpilation in VS Code for syntax highlighting is getting community support: github.com/microsoft/vs... Add a thumbs up on the issue if you think it's a good idea 😊

Here's the same exact thing but readable/maintainable, using Regex+ (can be minified to a regex literal using its Babel plugin).

oniguruma-to-es hits a big milestone with v2.0 by comprehensively supporting the extremely flexible \G anchor (which has no direct equivalent in JS regexes). See github.com/slevithan/on...

Ever wondered why there aren't good tools for converting between different regex flavors automatically? Would you use a universal regex translator in your own projects? Want to help build one? github.com/slevithan/on...

oniguruma-to-es v1.0.0 is out! ✨ The new release includes lots of edge case fixes reported by Oniguruma expert RedCMD, making its emulation even more accurate github.com/slevithan/on...

What do you think github.com/slevithan/re... is missing that would make it easier to use or make regexes in JavaScript better?

In 2024, we have redistributed a total of $4,371.83 USD to the open-source community! Thanks to everyone who supported this idea! 💖 Here is the recap: opencollective.com/antfu/update...

The biggest improvement most people can make to their mastery of regex is usually not learning more advanced features, but truly understanding *backtracking* This short article of mine from 2007 illustrates in depth the mechanics of regex backtracking: blog.stevenlevithan.com/archives/gre...

The path to supporting 100% of TextMate grammars in @shiki.style's JS engine: github.com/shikijs/shik...

Just shipped 3 library updates. 2024 saw a lot of OSS 🚢ing: New libs Regex+ (plus related babel-plugin-transform-regex, regex-recursion, regex-utilities), Oniguruma-To-ES, Awesome Regex, and emoji-regex-xs, plus new major versions of parseUri and Regex Colorizer. Can you guess the theme? 🤔

Would you use a JS library that added an optional timeout for regexes and worked in Node and browsers? Considering adding this to Regex+

Started late, but wrote more open source code this year than any other year before:

oniguruma-to-es v0.8 is now the best regex flavor→flavor translator in the world. Tell me if you disagree! Accurately translates 99.9% of real-world Oniguruma regexes, and it's hard to find any 2 regex flavors with more complex and nuanced differences than Oniguruma & JS. Will continue improving!

🎉 oniguruma-to-es 0.8.0 released, adding another large chunk of hard-fought grammars to @shiki.style's supported list when using its lightweight JS engine (which is < 4% of the size of the WASM regex engine). 95% of all grammars (> 99.9% of all regexes) now supported. github.com/slevithan/on...

Longtime fan of @dr-axel.de's books and work. Welcome to 🦋

Thanks for the sponsorship! 🙏

The JS engine for @shiki.style improves yet again with the latest version of oniguruma-to-es: github.com/shikijs/shik... (+1 grammar supported, and improved perf for most grammars)

🌈 Shiki v1.23 just dropped with massive updates: - New JavaScript engine by @slev.life that supports more languages - New Colorized Brackets package by michaelmakes.games - FS-based Twoslash cache by @nakasyou.bsky.social - New Style-to-Class transformer 👇 github.com/shikijs/shik...

Oniguruma-To-ES v0.3.0 now supports the vast majority of ways that recursion is used, including indirect recursion and multiple recursions in the same pattern — further increasing the number of supported grammars when used with Shiki syntax highlighter. github.com/slevithan/on... cc @antfu.me

Regex+ (formerly `regex`) recently crossed 500 ⭐s, 500K mo. dls, and 5 mo. since initial release (19 releases). 🎉 This is the regex library I've wanted since ES6 added tagged templates. Try it out -- I think you'll find the "regexes are unreadable" reputation is outdated. github.com/slevithan/re...