Simple Rust to Node native bridge
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RuNo bridge Simple Rust to NodeJS bridge

A Prototype! Please read whole readme first and use on your own risk!

Build Status

Call your Rust dynamic lib from Node JS with native C++ performance

Do not hesitate to ask a question or propose something, I've created a special discussion issue for your convenience:

RuNo bridge is a command line tool which generates C++ boilerplate addon code to call Rust library from. It is not allmighty and only support primitives such as int, float/double, bool and a string at a moment, however it does not require any C++ knowledge from developer if you use primitives mentioned above and your Rust ABI interface complies with simple requirements:

  • All your ABI functoins should be listed in one Rust file;
  • Your library should use crate libc;
  • Each ABI function should be preceeded with #[no_mangle];
  • Each ABI function should be prefixed with pub extern "C";
  • ABI Functions should only take params of c_int,c_float,c_double or *c_char (as a C string with EOF);
  • ABI Functions should return either one of c_int,c_float,c_double or *c_char (as a C string with EOF)

RuNo bridge does not validate or compiles your Rust code, we presume that it is valid and compiles.

See in tests for example of compatible Rust code. Take this file as a source of true for current version.

See for more standalone usage example


This package itself does not need Rust or C++ with node-gyp, it just emits a C++ source file.

However in order to build the source code, your rust and C++ compiler should be compatible with your NodeJS. It is particularly important on Windows, where Rust target should be MSVC not GNU, unless you building your NodeJS for Windows from source with GCC. For example, if one using 32 bit NodeJS on Windows this one should use target i686-pc-windows-msvc, if 64 bit Node then Rust should be configured with x86_64-pc-windows-msvc compile target. The same about C++: Everything is mostrly smooth on platforms with GCC, and a bit painful with MS Visual C++, please refer to node-gyp installation instructions for details.


npm install runo-bridge -g
  • global option used here for simplisity, however it is better to install it locally and run it as local npm binary.


Generate V8 addon C++ code from Rust source

runo-bridge generate <source> <output> [options]

Options available:

--async [NO|ALL|DETECT] - With this option it is possible to make functions async. You don't need to mangle with V8 callbacks, RuNo will generate C++ boilerplate code for you, which will run function in a separate thread, take result from the function and pass value into callback. Again you just write a normal function and RuNo will do all thread magic for you.

  • NO do not wrap functions into async wrappers (default);
  • ALL all functions will be called in a separate thread, adding last param as a callback with result argument;
  • DETECT detect functions with 'async' and make them async as described above;

See double_multiply_plus2_async in and integration/test.js for async usage example.


runo-bridge generate src/ intermediates/

RuNo will look for no-manlge extern "C" functions and will generate NodeJS addon boilerplate for them.

runo-bridge generate src/ intermediates/ --async DETECT

same as above, plus detect functions with 'async' in the name and generate boilerplate code to run then asynchronously, adding last param as an async callback with a single param with a function result.

It is also possible to provide library binary interface definition as a JSON

runo-bridge generate src/my-interface.json intermediates/

See example JSON format in input.json . Theoretically you can use this approach with any precompiled C ABI compatible dynamic library.


Do npm install first.

Test RuNo bridge only:

npm run test

Test that generated addon actually works (integration tests):

npm run test-full


It would be nice to have something simple to use with just implementing extern C method with C primitives without knowledge of V8. FFI seems to be a good option, however, unfortunately it is far to slow to call multiple functions, see:

Other options