Oniguruma-To-ES
Translates Oniguruma regex patterns (used by Ruby, TextMate, VS Code) to native JavaScript RegExp with high accuracy.
What is Oniguruma-To-ES?
Oniguruma-To-ES is a JavaScript library that translates Oniguruma regular expression patterns into native JavaScript RegExp. It solves the problem of using regexes written for Ruby, TextMate grammars (like those in VS Code and Shiki), or PHP in JavaScript environments, bridging syntax and behavioral gaps between the engines.
Developers working with TextMate grammars for syntax highlighting, those sharing regexes between Ruby/PHP and JavaScript codebases, and anyone needing to run Oniguruma-style regexes in JavaScript with high accuracy.
It provides near-perfect translation fidelity for real-world Oniguruma regexes, often outperforms WASM-based alternatives in speed and bundle size, and supports modern JavaScript targets with advanced emulation features unavailable in other translators.
Overview
👹 Convert patterns from Oniguruma (the regex flavor used by Ruby, TextMate grammars, etc.) to native JavaScript RegExp
Use Cases
Best For
- Converting TextMate grammar regexes for use in JavaScript syntax highlighters like Shiki
- Sharing regex patterns between Ruby/Rails and JavaScript/Node.js applications
- Running Oniguruma regexes from PHP's mb_ereg functions in JavaScript environments
- Utilizing Oniguruma's extended features (e.g., atomic groups, recursion) in JavaScript projects
- Improving performance over vscode-oniguruma WASM for regex matching in browsers
- Precompiling regexes to minimize bundle size in frontend tooling
Not Ideal For
- Projects requiring emulation of overlapping recursions or named callouts, which are explicitly unsupported per the README
- Environments locked to JavaScript versions older than ES2018, as features like character class intersection require ES2024+ targets
- Teams that prioritize drop-in WASM solutions over transpilation, especially if absolute feature parity for all Oniguruma features is critical
- Use cases relying heavily on Unicode blocks (with the 'In' prefix), which are omitted to keep the library lightweight
Pros & Cons
Pros
Supports ~99.99% of real-world Oniguruma regexes, accurately handling hundreds of syntax and behavioral differences, as tested on tens of thousands of TextMate grammar patterns.
Generated regexes run as native JavaScript, often faster than WASM-based alternatives like vscode-oniguruma, with a bundle size ~4% of it, reducing browser load times.
Outputs regexes compatible with ES2018, ES2024, or ES2025 targets, leveraging features like flag 'v' and flag groups for cleaner, more efficient patterns.
Accurately emulates complex Oniguruma features like atomic groups, possessive quantifiers, and recursion with identical behavior, even in extreme edge cases.
Allows precompiling regexes to eliminate runtime dependencies, and the tree-shakable EmulatedRegExp subclass minimizes bundle size for advanced features.
Cons
A few extremely rare Oniguruma features, such as overlapping recursions and named callouts, are not supported and throw errors, though they affect less than 0.01% of real-world regexes.
Advanced emulation requires the EmulatedRegExp RegExp subclass, which can complicate integration with code expecting native RegExp objects and may not be fully compatible in all environments.
Full feature support, like character class intersection, requires ES2024 or later, restricting use in older environments without upgrades or workarounds.
Numerous options like accuracy, target, and rules can be overwhelming for simple conversions and require careful tuning to avoid errors or suboptimal results.
Open Source Alternative To
Oniguruma-To-ES is an open-source alternative to the following products:
Frequently Asked Questions
Related Projects
Regex+JS regexes ➕ future. A template tag for readable, high-performance, native JS regexes with extended syntax, context-aware interpolation, and always-on best practices.
node-re2Bindings for RE2: fast, safe alternative to backtracking regular expression engines.
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