[](https://crates.io/crates/rustyscript/)
[](https://github.com/rscarson/rustyscript/actions?query=branch%3Amaster)
[](https://docs.rs/rustyscript/latest/rustyscript/)
[](https://rscarson.github.io/rustyscript-book/)
[](https://raw.githubusercontent.com/rscarson/rustyscript/master/LICENSE)
## Rustyscript - Effortless JS Integration for Rust
rustyscript provides 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 aims 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.
**Sandboxed**
By default, the code being run is entirely sandboxed from the host, having no filesystem or network access.
[extensions](https://rscarson.github.io/rustyscript-book/extensions) can be added to grant additional capabilities that may violate sandboxing
**Flexible**
The runtime is designed to be as flexible as possible, allowing you to modify capabilities, the module loader, and more.
- Asynchronous JS is fully supported, and the runtime can be configured to run in a multithreaded environment.
- Typescript is supported, and will be transpired into JS for execution.
- Node JS is supported experimentally, but is not yet fully compatible ([See the `NodeJS` Compatibility section](https://rscarson.github.io/rustyscript-book/advanced/nodejs_compatibility.md))
**Unopinionated**
Rustyscript is designed to be a thin wrapper over the Deno runtime, to remove potential pitfalls and simplify the API without sacrificing flexibility or performance.
-----
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
```rust
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:
```rust
let result: i64 = rustyscript::evaluate("5 + 5").expect("The expression was invalid!");
```
Or to just import a single module for use:
```rust
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`]:
```rust
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:
```rust
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`]
```rust
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`]
```rust
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:
```rust
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
Commonly used features have been grouped into the following feature-sets:
- **`safe_extensions`** - On by default, these extensions are safe to use in a sandboxed environment
- **`network_extensions`** - These extensions break sandboxing by allowing network connectivity
- **`io_extensions`** - These extensions break sandboxing by allowing filesystem access (WARNING: Also allows some network access)
- **`all_extensions`** - All 3 above groups are included
- **`extra_features`** - Enables the `worker` feature (enabled by default), and the `snapshot_builder` feature
- **`node_experimental`** - HIGHLY EXPERIMENTAL nodeJS support that enables all available Deno extensions
## 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
|`broadcast_channel`|Implements the web-messaging API for Deno |**NO** |`deno_broadcast_channel`, `deno_web`, `deno_webidl` |
|`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`, `deno_terminal` |
|`cron` |Implements scheduled tasks (crons) API |**NO** |`deno_cron`, `deno_console` |
|`crypto` |Provides `crypto.*` functionality from JS |yes |`deno_crypto`, `deno_webidl` |
|`ffi` |Dynamic library ffi features |**NO** |`deno_ffi` |
|`fs` |Provides ops for interacting with the file system. |**NO** |`deno_fs`, `web`, `io` |
|`http` |Implements the fetch standard |**NO** |`deno_http`, `web`, `websocket` |
|`kv` |Implements the Deno KV Connect protocol |**NO** |`deno_kv`, `web`, `console` |
|`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` |
|`webgpu` |Implements the WebGPU API |**NO** |`deno_webgpu`, `web` |
|`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` |
| | | | |
|`node_experimental`|HIGHLY EXPERIMENTAL nodeJS support that enables all available Deno extensions |**NO** |For complete list, see Cargo.toml |
| | | | |
|`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` |
----
For an example of this crate in use, see [Lavendeux](https://github.com/rscarson/lavendeux)