Crate rustyscript

Expand description

This crate is meant to provide a quick and simple way to integrate a runtime javascript or typescript component from within rust.

It uses the v8 engine through the deno_core crate, and is meant to be as simple as possible to use without sacrificing flexibility or performance.

I also have attempted to abstract away the v8 engine details so you can for the most part operate directly on rust types.

By default, the code being run is entirely sandboxed from the host, having no filesystem or network access.
- It can be extended to include those capabilities and more if desired - please see the ‘web’ feature, and the ‘runtime_extensions’ example
Asynchronous JS code is supported (I suggest using the timeout option when creating your runtime)
Loaded JS modules can import other modules
Typescript is supported by default, and will be transpiled into JS for execution

Here is a very basic use of this crate to execute a JS module. It will:

Create a basic runtime
Load a javascript module,
Call a function registered as the entrypoint
Return the resulting value

use rustyscript::{json_args, Runtime, Module, Error};

let module = Module::new(
    "test.js",
    "
    export default (string, integer) => {
        console.log(`Hello world: string=${string}, integer=${integer}`);
        return 2;
    }
    "
);

let value: usize = Runtime::execute_module(
    &module, vec![],
    Default::default(),
    json_args!("test", 5)
)?;

assert_eq!(value, 2);

Modules can also be loaded from the filesystem with Module::load or Module::load_dir if you want to collect all modules in a given directory.

If all you need is the result of a single javascript expression, you can use:

let result: i64 = rustyscript::evaluate("5 + 5").expect("The expression was invalid!");

Or to just import a single module for use:

use rustyscript::{json_args, import};
let mut module = import("js/my_module.js").expect("Something went wrong!");
let value: String = module.call("exported_function_name", json_args!()).expect("Could not get a value!");

There are a few other utilities included, such as validate and resolve_path

A more detailed version of the crate’s usage can be seen below, which breaks down the steps instead of using the one-liner Runtime::execute_module:

use rustyscript::{json_args, Runtime, RuntimeOptions, Module, Error, Undefined};
use std::time::Duration;

let module = Module::new(
    "test.js",
    "
    let internalValue = 0;
    export const load = (value) => internalValue = value;
    export const getValue = () => internalValue;
    "
);

// Create a new runtime
let mut runtime = Runtime::new(RuntimeOptions {
    timeout: Duration::from_millis(50), // Stop execution by force after 50ms
    default_entrypoint: Some("load".to_string()), // Run this as the entrypoint function if none is registered
    ..Default::default()
})?;

// The handle returned is used to get exported functions and values from that module.
// We then call the entrypoint function, but do not need a return value.
//Load can be called multiple times, and modules can import other loaded modules
// Using `import './filename.js'`
let module_handle = runtime.load_module(&module)?;
runtime.call_entrypoint::<Undefined>(&module_handle, json_args!(2))?;

// Functions don't need to be the entrypoint to be callable!
let internal_value: i64 = runtime.call_function(Some(&module_handle), "getValue", json_args!())?;

There are also ‘_async’ and ‘immediate’ versions of most runtime functions; ‘_async’ functions return a future that resolves to the result of the operation, while ‘_immediate’ functions will make no attempt to wait for the event loop, making them suitable for using crate::js_value::Promise

Rust functions can also be registered to be called from javascript:

use rustyscript::{ Runtime, Module, serde_json::Value };

let module = Module::new("test.js", " rustyscript.functions.foo(); ");
let mut runtime = Runtime::new(Default::default())?;
runtime.register_function("foo", |args| {
    if let Some(value) = args.get(0) {
        println!("called with: {}", value);
    }
    Ok(Value::Null)
})?;
runtime.load_module(&module)?;

Asynchronous JS can be called in 2 ways;

The first is to use the ‘async’ keyword in JS, and then call the function using Runtime::call_function_async

use rustyscript::{ Runtime, Module, json_args };

let module = Module::new("test.js", "export async function foo() { return 5; }");
let mut runtime = Runtime::new(Default::default())?;

// The runtime has its own tokio runtime; you can get a handle to it with [Runtime::tokio_runtime]
// You can also build the runtime with your own tokio runtime, see [Runtime::with_tokio_runtime]
let tokio_runtime = runtime.tokio_runtime();

let result: i32 = tokio_runtime.block_on(async {
    // Top-level await is supported - we can load modules asynchronously
    let handle = runtime.load_module_async(&module).await?;

    // Call the function asynchronously
    runtime.call_function_async(Some(&handle), "foo", json_args!()).await
})?;

assert_eq!(result, 5);

The second is to use crate::js_value::Promise

use rustyscript::{ Runtime, Module, js_value::Promise, json_args };

let module = Module::new("test.js", "export async function foo() { return 5; }");

let mut runtime = Runtime::new(Default::default())?;
let handle = runtime.load_module(&module)?;

// We call the function without waiting for the event loop to run, or for the promise to resolve
// This way we can store it and wait for it later, without blocking the event loop or borrowing the runtime
let result: Promise<i32> = runtime.call_function_immediate(Some(&handle), "foo", json_args!())?;

// We can then wait for the promise to resolve
// We can do so asynchronously, using [crate::js_value::Promise::into_future]
// But we can also block the current thread:
let result = result.into_value(&mut runtime)?;
assert_eq!(result, 5);

See Runtime::register_async_function for registering and calling async rust from JS
See ‘examples/async_javascript.rs’ for a more detailed example of using async JS

For better performance calling rust code, consider using an extension instead of a module - see the ‘runtime_extensions’ example for details

A threaded worker can be used to run code in a separate thread, or to allow multiple concurrent runtimes.

the worker module provides a simple interface to create and interact with workers. The worker::InnerWorker trait can be implemented to provide custom worker behavior.

It also provides a default worker implementation that can be used without any additional setup:

use rustyscript::{Error, worker::{Worker, DefaultWorker, DefaultWorkerOptions}};
use std::time::Duration;

fn main() -> Result<(), Error> {
    let worker = DefaultWorker::new(DefaultWorkerOptions {
        default_entrypoint: None,
        timeout: Duration::from_secs(5),
    })?;

    let result: i32 = worker.eval("5 + 5".to_string())?;
    assert_eq!(result, 10);
    Ok(())
}

§Utility Functions

These functions provide simple one-liner access to common features of this crate:

evaluate; Evaluate a single JS expression and return the resulting value
import; Get a handle to a JS module from which you can get exported values and functions
resolve_path; Resolve a relative path to the current working dir
validate; Validate the syntax of a JS expression
init_platform; Initialize the V8 platform for multi-threaded applications

§Crate features

The table below lists the available features for this crate. Features marked at Preserves Sandbox: NO break isolation between loaded JS modules and the host system. Use with caution.

More details on the features can be found in Cargo.toml

Please note that the ‘web’ feature will also enable fs_import and url_import, allowing arbitrary filesystem and network access for import statements

This is because the deno_web crate allows both fetch and FS reads already

Feature	Description	Preserves Sandbox	Dependencies
cache	Implements the Cache API for Deno	NO	deno_cache, deno_webidl, deno_web, deno_crypto, deno_fetch, deno_url, deno_net
console	Provides `console.*` functionality from JS	yes	deno_console
crypto	Provides `crypto.*` functionality from JS	yes	deno_crypto, deno_webidl
url	Provides the URL, and URLPattern APIs from within JS	yes	deno_webidl, deno_url
io	Provides IO primitives such as stdio streams and abstraction over File System files.	NO	deno_io, rustyline, winapi, nix, libc, once_cell
web	Provides the Event, TextEncoder, TextDecoder, File, Web Cryptography, and fetch APIs from within JS	NO	deno_webidl, deno_web, deno_crypto, deno_fetch, deno_url, deno_net
webstorage	Provides the WebStorage API	NO	deno_webidl, deno_webstorage
websocket	Provides the WebSocket API	NO	deno_web, deno_websocket
webidl	Provides the webidl API	yes	deno_webidl

default	Provides only those extensions that preserve sandboxing	yes	deno_console, deno_crypto, deno_webidl, deno_url
no_extensions	Disables all extensions to the JS runtime - you can still add your own extensions in this mode	yes	None
all	Provides all available functionality	NO	deno_console, deno_webidl, deno_web, deno_net, deno_crypto, deno_fetch, deno_url

fs_import	Enables importing arbitrary code from the filesystem through JS	NO	None
url_import	Enables importing arbitrary code from network locations through JS	NO	reqwest

worker	Enables access to the threaded worker API worker	yes	None
snapshot_builder	Enables access to [SnapshotBuilder], a runtime for creating snapshots that can improve start-times	yes	None
web_stub	Enables a subset of `web` features that do not break sandboxing	yes	deno_webidl

Please also check out @Bromeon/js_sandbox, another great crate in this niche

Re-exports§

pub use error::Error;
pub use deno_core;
pub use deno_core::serde_json;
pub use tokio;

Modules§

cache_provider
This module provides a trait for caching module data for the loader
error
Contains the error type for the runtime And some associated utilities
js_value
This module provides a way to store and use javascript values, functions, and promises The are a deserialized version of the v8::Value
worker
Provides a worker thread that can be used to run javascript code in a separate thread through a channel pair It also provides a default worker implementation that can be used without any additional setup:

Macros§

async_callback
A simple helper macro to create a callback for use with Runtime::register_async_function Takes care of deserializing arguments and serializing the result
json_args
Map a series of values to a slice of serde_json::Value objects that javascript functions can understand
module
Creates a static module
sync_callback
A simple helper macro to create a callback for use with Runtime::register_function Takes care of deserializing arguments and serializing the result

Structs§

ExtensionOptions
Options for configuring extensions
Module
Represents a pice of javascript for execution.
ModuleHandle
Represents a loaded instance of a module within a runtime
ModuleWrapper
A wrapper type representing a runtime instance loaded with a single module Exactly equivalent to Runtime::new followed by Runtime::load_module
Runtime
A runtime instance that can be used to execute JavaScript code and interact with it Most runtime functions have 3 variants - blocking, async, and immediate For example:
StaticModule
A static representation of a module use .to_module() to get a module instance to use with a runtime

Traits§

RsAsyncFunction
Represents an async function that can be registered with the runtime
RsFunction
Represents a function that can be registered with the runtime

Functions§

evaluate
Evaluate a piece of non-ECMAScript-module JavaScript code Effects on the global scope will not persist For a persistant variant, see Runtime::eval
import
Imports a JS module into a new runtime
init_platform
Explicitly initialize the V8 platform Note that all runtimes must have a common parent thread that initalized the V8 platform
resolve_path
Resolve a path to absolute path
validate
Validates the syntax of some JS

Type Aliases§

FunctionArguments
Type required to pass arguments to Functions
RuntimeOptions
Represents the set of options accepted by the runtime constructor
Undefined
For functions returning nothing. Acts as a placeholder for the return type Should accept any type of value from javascript

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