Small and modular JavaScript runtime for desktop and mobile. Like Node.js, it provides an asynchronous, event-driven architecture for writing applications in the lingua franca of modern software. Unlike Node.js, it makes embedding and cross-device support core use cases, aiming to run just as well on your phone as on your laptop. The result is a runtime ideal for networked, peer-to-peer applications that can run on a wide selection of hardware.

Prebuilt binaries are provided by https://github.com/holepunchto/bare-runtime and can be installed using npm:

npm i -g bare-runtime

bare [-e, --eval <script>] [-p, --print <script>] [<filename>]

The specified <script> or <filename> is run using Module.load(). For more information on the module system and the supported formats, see https://github.com/holepunchto/bare-module.

Bare is built on top of https://github.com/holepunchto/libjs, which provides low-level bindings to V8, and https://github.com/libuv/libuv, which provides an asynchronous I/O event loop. Bare itself only adds a few missing pieces on top to support a wider ecosystem of modules:

1. A module system supporting both CJS and ESM with bidirectional interoperability between the two.
2. A native addon system supporting both statically and dynamically linked addons.
3. Light-weight thread support with synchronous joins and shared array buffer support.

Everything else if left to userland modules to implement using these primitives, keeping the runtime itself succint and bare.

The core JavaScript API of Bare is available through the global Bare namespace.

The identifier of the operating system for which Bare was compiled. The possible values are android, darwin, ios, linux, and win32.

The identifier of the processor architecture for which Bare was compiled. The possible values are arm, arm64, ia32, and x64.

The command line arguments passed to the process when launched.

The ID of the current process.

The code that will be returned once the process exits. If the process is exited using Bare.exit() without specifying a code, Bare.exitCode is used.

Whether or not the process is currently suspended.

Whether or not the process is currently exiting.

The Bare version string.

An object containing the version strings of Bare and its dependencies.

Immediately terminate the process or current thread with an exit status of code which defaults to Bare.exitCode.

Suspend the process and all threads. This will emit a suspend event signalling that all work should stop immediately. When all work has stopped and the process would otherwise exit, an idle event will be emitted. If the process is not resumed from an idle event listener and no additional work is scheduled, the loop will block until the process is resumed. If additional work is scheduled from an idle event, the idle event will be emitted again once all work has stopped unless the process was resumed.

Resume the process and all threads after suspension. This can be used to cancel suspension after the suspend event has been emitted and up until all idle event listeners have run.

Emitted when a JavaScript exception is thrown within an exectuion context without being caught by any exception handlers within that execution context. By default, uncaught exceptions are printed to stderr and the processes aborted. Adding an event listener for the uncaughtException event overrides the default behavior.

Emitted when a JavaScript promise is rejected within an execution context without that rejection being handled within that execution context. By default, unhandled rejections are printed to stderr and the process aborted. Adding an event listener for the unhandledRejection event overrides the default behavior.

Emitted when the loop runs out of work and before the process or current thread exits. This provides a chance to schedule additional work and keep the process from exiting. If additional work is scheduled, beforeExit will be emitted again once the loop runs out of work.

If the process is exited explicitly, such as by calling Bare.exit() or as the result of an uncaught exception, the beforeExit event will not be emitted.

Emitted just before the process or current thread terminates. Additional work scheduled from an exit event listener will be given a chance to run after which the process will terminate. If the process is forcefully terminated from an exit event listener, the remaining listeners will not run.

Emitted after the process or current thread has terminated and just before the JavaScript environment is torn down. Additional work must not be scheduled from a teardown event listener. Bare itself will register teardown event listeners to join dangling threads and unload native addons.

Bare.prependListener('teardown', () => { ... })

Emitted when the process or current thread is suspended. Any in-progress or outstanding work, such as network activity or file system access, should be deferred, cancelled, or paused when the suspend event is emitted and no additional work may be scheduled.

Emitted when the process or current thread becomes idle after suspension. If no additional work is scheduled from this event, the loop will block and no additional work be performed until the process is resumed. An idle event listener may call Bare.resume() to cancel the suspension.

Emitted when the process or current thread resumes after suspension. Deferred and paused work should be continued when the resume event is emitted and new work may again be scheduled.

The Bare.Addon namespace provides support for loading native addons, which are typically written in C/C++ and distributed as shared libraries.

Load a static or dynamic native addon identified by url. If url is not a static native addon, Bare will instead look for a matching dynamic object library.

Unload a dynamic native addon identified by url. If the function returns true, the addon was unloaded from memory. If it instead returns false, the addon is still in use by one or more threads and will only be unloaded from memory when those threads either exit or explicitly unload the addon.

Resolve a native addon specifier by searching for a static native addon or dynamic object library matching specifier imported from parentURL.

Options include:

{
  // The name of the addon. If `null`, it will instead be read from the
  // resolved `package.json`.
  name: null,
  // The version of the addon. If `null`, it will instead be read from the
  // resolved `package.json`.
  version: null
}

The Bare.Thread provides support for lightweight threads. Threads are similar to workers in Node.js, but provide only minimal API surface for creating and joining threads.

true if the current thread is the main thread.

A reference to the current thread as a ThreadProxy object. Will be null on the main thread.

A copy of or, if shared, reference to the data buffer that was passed to the current thread on creation. Will be null if no buffer was passed.

Start a new thread that will run the contents of filename. If callback is provided, its function body will be treated as the contents of filename and invoked on the new thread with Thread.self.data passed as an argument.

Options include:

{
  // Optional data to pass to the thread
  data: Buffer | ArrayBuffer | SharedArrayBuffer | External,
  // Optional file source, will be read from `filename` if neither `source` nor `callback` are provided
  source: string | Buffer,
  // Optional source encoding if `source` is a string
  encoding: 'utf8',
  // Optional stack size in bytes, pass 0 for default
  stackSize: 0
}

Convenience method for the new Thread() constructor

Whether or not the thread has been joined with the current thread.

Block and wait for the thread to exit.

Bare provides no standard library beyond the core JavaScript API available through the Bare namespace. Instead, we maintain a comprehensive collection of external modules built specifically for Bare:

Bare can easily be embedded using the C API defined in include/bare.h:

#include <bare.h>
#include <uv.h>

bare_t *bare;
bare_setup(uv_default_loop(), platform, &env, argc, argv, options, &bare);

bare_run(bare, filename, source);

int exit_code;
bare_teardown(bare, &exit_code);

If source is NULL, the contents of filename will instead be read at runtime. For examples of how to embed Bare on mobile platforms, see https://github.com/holepunchto/bare-android and https://github.com/holepunchto/bare-ios.

Bare provides a mechanism for implementing process suspension, which is needed for platforms with strict application lifecycle constraints, such as mobile platforms. When suspended, a suspend event will be emitted on the Bare namespace. Then, when the loop has no work left and would otherwise exit, an idle event will be emitted and the loop blocked, keeping it from exiting. When the process is later resumed, a resume event will be emitted and the loop unblocked, allowing it to exit when no work is left.

The suspension API is available through bare_suspend() and bare_resume() from C and Bare.suspend() and Bare.resume() from JavaScript. See example/suspend.js for an example of using the suspension API from JavaScript.

The bare-dev toolkit, which we'll be invoking with npx, is used for building Bare and acts as a convenient wrapper around CMake and other tools. After cloning the repository, start by synchronising the vendored dependencies such as git submodules:

npx bare-dev vendor sync

Then, configure the build tree before performing the first build:

npx bare-dev configure [--debug]

Finally, perform the build:

npx bare-dev build

When completed, the bare binary will be available in the build/bin directory and the libbare.(a|lib) and (lib)bare.(dylib|dll) libraries will be available in the root of the build directory.

When linking against the static libbare.(a|lib) library, make sure to use whole archive linking as Bare relies on constructor functions for registering native addons. Without whole archive linking, the linker will remove the constructor functions as they aren't referenced by anything.

Apache-2.0