A standard library for the client-side Web

The goal of this crate is to provide Rust bindings to the Web APIs and to allow a high degree of interoperability between Rust and JavaScript.

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Patrons

This software was brought to you thanks to these wonderful people:

• Eduard Knyshov
• Anselm Eickhoff
• Ferran Pujol Camins
• Johan Andersson
• Stephen Sugden

Thank you!

Examples

You can directly embed JavaScript code into Rust:

let message = "Hello, 世界!";
let result = js! {
    alert( @{message} );
    return 2 + 2 * 2;
};

println!( "2 + 2 * 2 = {:?}", result );

Closures are also supported:

let print_hello = |name: String| {
    println!( "Hello, {}!", name );
};

js! {
    var print_hello = @{print_hello};
    print_hello( "Bob" );
    print_hello.drop(); // Necessary to clean up the closure on Rust's side.
}

You can also pass arbitrary structures thanks to serde:

#[derive(Serialize)]
struct Person {
    name: String,
    age: i32
}

js_serializable!( Person );

js! {
    var person = @{person};
    console.log( person.name + " is " + person.age + " years old." );
};

This crate also exposes a number of Web APIs, for example:

let button = document().query_selector( "#hide-button" ).unwrap().unwrap();
button.add_event_listener( move |_: ClickEvent| {
    for anchor in document().query_selector_all( "#main a" ) {
        js!( @{anchor}.style = "display: none;"; );
    }
});

Exposing Rust functions to JavaScript is supported too:

#[js_export]
fn hash( string: String ) -> String {
    let mut hasher = Sha1::new();
    hasher.update( string.as_bytes() );
    hasher.digest().to_string()
}

Then you can do this from Node.js:

var hasher = require( "hasher.js" ); // Where `hasher.js` is generated from Rust code.
console.log( hasher.hash( "Hello world!" ) );

Or you can take the same .js file and use it in a web browser:

<script src="hasher.js"></script>
<script>
    Rust.hasher.then( function( hasher ) {
        console.log( hasher.hash( "Hello world!" ) );
    });
</script>

If you're using Parcel you can also use our experimental Parcel plugin; first do this in your existing Parcel project:

$ npm install --save parcel-plugin-cargo-web

And then simply:

import hasher from "./hasher/Cargo.toml";
console.log( hasher.hash( "Hello world!" ) );

Design goals

• Expose a full suite of Web APIs as exposed by web browsers.
• Try to follow the original JavaScript conventions and structure as much as possible, except in cases where doing otherwise results in a clearly superior design.
• Be a building block from which higher level frameworks and libraries can be built.
• Make it convenient and easy to embed JavaScript code directly into Rust and to marshal data between the two.
• Integrate with the wider Rust ecosystem, e.g. support marshaling of structs which implement serde's Serializable.
• Put Rust in the driver's seat where a non-trivial Web application can be written without touching JavaScript at all.
• Allow Rust to take part in the upcoming WebAssembly (re)volution.
• Make it possible to trivially create standalone libraries which are easily callable from JavaScript.

Getting started

Take a look at some of the examples:

• examples/minimal - a totally minimal example which calls alert
• examples/todomvc - a naively implemented TodoMVC application; shows how to call into the DOM
• examples/hasher - shows how to export Rust functions to JavaScript and how to call them from a vanilla web browser environment or from Nodejs
• examples/hasher-parcel - shows how to import and call exported Rust functions in a Parcel project
• pinky-web - an NES emulator; you can play with the precompiled version here

Running the examples

1. Install cargo-web:

   $ cargo install -f cargo-web
   

2. Go into examples/todomvc and start the example using one of these commands:

   • Compile to WebAssembly using Rust's native WebAssembly backend (requires Rust nightly!):

     $ cargo web start --target=wasm32-unknown-unknown
     

   • Compile to asm.js using Emscripten:

     $ cargo web start --target=asmjs-unknown-emscripten
     

   • Compile to WebAssembly using Emscripten:

     $ cargo web start --target=wasm32-unknown-emscripten
     

3. Visit http://localhost:8000 with your browser.

For the *-emscripten targets cargo-web is not necessary, however the native wasm32-unknown-unknown which doesn't need Emscripten requires cargo-web to work!

Changelog

• stdweb 0.4.10, stdweb-derive 0.5.1

  • New methods:
    • IElement::insert_adjacent_html
    • IElement::insert_html_before
    • IElement::insert_html_after
    • IElement::prepend_html
    • IElement::append_html
    • IElement::namespace_uri
    • IElement::closest
    • Document::create_element_ns
    • Window::get_selection
  • New types:
    • AbortError
    • SelectionType
    • Selection
    • Range
  • The error messages for failed type conversions are now improved
  • The error type of failed conversions (when using .try_into()/.try_from()) is now convertible into a TypeError
  • Aggregate error types (like, e.g. DrawImageError) are now serializable through the js! macro
  • TypeError is now fixed (it was incorrectly treated as a DOMException)
  • Number can now be converted into f64 with .into()/.from()
  • Added Mut, which is a new wrapper type for safely passing FnMut closures into the js! macro; it is optional for now, however the usage of this wrapper type will be mandatory in the future!
  • FnMut closures cannot be called recursively anymore
  • #[derive(ReferenceType)] now supports a limited subset of generic types
  • Asynchronous unit tests are now supported with a new #[async_test] attribute macro (nightly only)
  • Updated to futures 0.3 (nightly only)

• stdweb 0.4.9, stdweb-derive 0.5.0

  • Performance improvements; serialization through serde is now twice as fast
  • New events:
    • ScrollEvent
    • DragRelatedEvent
    • DragEvent
    • DragStartEvent
    • DragEndEvent
    • DragEnterEvent
    • DragLeaveEvent
    • DragOverEvent
    • DragExitEvent
    • DragDropEvent
  • New types:
    • DataTransfer
    • EffectAllowed
    • DropEffect
    • DataTransferItemList
    • DataTransferItem
    • DataTransferItemKind
    • IDragEvent
  • Values can now be converted to Option< Serde< T > > with try_into
  • Deserialization of numbers through serde now works in the majority of cases allowing types other than i32 and f64 to be used
  • All of the events are now more strongly-typed
    • Previously in was possible to deserialize e.g. a keyup event as a KeyDownEvent since only the event's JS type was checked and both keyup and keydown share the same JS type (KeyboardEvent). From now on the type field of the event is also checked, so such conversions are not allowed anymore.

• 0.4.8

  • Fixed compilation on the newest nightly when targeting wasm32-unknown-unknown
  • New events:
    • PointerLockChangeEvent
    • PointerLockErrorEvent
    • MouseWheelEvent
  • New types:
    • MouseWheelDeltaMode
    • XhrResponseType
  • New methods:
    • XmlHttpRequest::raw_response
    • Window::device_pixel_ratio
    • Document::pointer_lock_element
    • Document::exit_pointer_lock

• 0.4.7

  • New events:
    • AuxClickEvent
    • MouseEnterEvent
    • MouseLeaveEvent
    • ContextMenuEvent
    • SelectionChangeEvent
  • New types:
    • FileList
    • FileReaderReadyState
  • Implement gamepad APIs:
    • Gamepad
    • GamepadButton
    • GamepadButtonMapping
    • GamepadEvent
  • Fixed CanvasRenderingContext2d::clear_rect
  • Fixed a leak when creating TypedArrays from Vecs and ArrayBuffers.

• 0.4.6

  • Fix docs.rs again
  • New types:
    • SubmitEvent
    • IChildNode
  • Fix CanvasElement::to_data_url

• 0.4.5

  • New types:
    • DocumentFragment
    • SelectElement
    • OptionElement
    • HtmlCollection
  • New methods:
    • Node::from_html
    • Value::is_null
  • Expose enums:
    • SocketMessageData
    • NodeType
  • Update to futures 0.2

• 0.4.4

  • Fix docs.rs (hopefully).
  • New methods:
    • Location::origin
    • Location::protocol
    • Location::host
    • Location::hostname
    • Location::port
    • Location::pathname
    • Location::search
  • These now return SecurityError in the error case:
    • Location::hash
    • Location::href

• 0.4.3

  • Objects which cannot be used as keys in a WeakMap should be supported now (e.g. some of the WebGL-related objects under Firefox)
  • New methods:
    • Element::get_bounding_client_rect
    • Element::scroll_top
    • Element::scroll_left
    • Window::page_x_offset
    • Window::page_y_offset
    • NodeList::item
    • Document::body
    • Document::head
    • Document::title
    • Document::set_title
    • IMouseEvent::offset_x
    • IMouseEvent::offset_y
  • Expose more canvas related types:
    • CompositeOperation
    • LineCap
    • LineJoin
    • Repetition
    • TextAlign
    • TextBaseline
  • Expose canvas related error types: AddColorStopError, DrawImageError, GetImageDataError
  • New events:
    • MouseOverEvent
    • MouseOutEvent
    • PointerOverEvent
    • PointerEnterEvent
    • PointerDownEvent
    • PointerMoveEvent
    • PointerUpEvent
    • PointerCancelEvent
    • PointerOutEvent
    • PointerLeaveEvent
    • GotPointerCaptureEvent
    • LostPointerCaptureEvent
  • New interface for pointer events: IPointerEvent

• 0.4.2

  • Fixed a leak when deserializing references
  • Fixed CanvasRenderingContext2d::get_canvas
  • Exposed FillRule and SocketReadyState
  • New attribute related methods added to IElement
  • New Date bindings

• 0.4.1

  • Support for newest nightly Rust on wasm32-unknown-unknown
  • Exposed SocketBinaryType enum
  • New canvas APIs:
    • Numerous new methods for CanvasRenderingContext2d
    • New types: CanvasGradient, CanvasPattern, CanvasStyle, ImageData, TextMetrics
  • New error types: IndexSizeError, NotSupportedError, TypeError

• 0.4

  • (breaking change) Removed Array and Object variants from Value; these are now treated as References
  • (breaking change) The Value has an extra variant: Symbol
  • (breaking change) Removed:
    • InputElement::set_kind
    • InputElement::files
  • (breaking change) Renamed:
    • KeydownEvent -> KeyDownEvent
    • KeyupEvent -> KeyUpEvent
    • KeypressEvent -> KeyPressEvent
    • ReadyState -> FileReaderReadyState
    • InputElement::value -> InputElement::raw_value
    • InputElement::set_value -> InputElement::set_raw_value
  • (breaking change) ArrayBuffer::new now takes an u64 argument
  • (breaking change) InputElement::set_raw_value now takes &str instead of Into< Value >
  • (breaking change) Changed return types:
    • Every method which returned usize now returns u32
    • INode::remove_child now returns Node in the Ok case
    • The following now return an u64:
      • ArrayBuffer::len
    • The following now return an i32 instead of f64:
      • IMouseEvent::client_x
      • IMouseEvent::client_y
      • IMouseEvent::movement_x
      • IMouseEvent::movement_y
      • IMouseEvent::screen_x
      • IMouseEvent::screen_y
    • The following now return a Result:
      • INode::insert_before
      • INode::replace_child
      • INode::clone_node
      • StringMap::insert
      • TokenList::add
      • TokenList::remove
      • Document::create_element
      • IEventTarget::dispatch_event
      • FileReader::read_as_text
      • FileReader::read_as_array_buffer
      • FileReader::read_as_text
      • History::replace_state
      • History::go
      • History::back
      • History::forward
      • Location::href
      • Location::hash
      • CanvasElement::to_data_url
      • CanvasElement::to_blob
      • ArrayBuffer::new
    • INode::base_uri now returns a String instead of Option< String >
    • InputElement::raw_value now returns a String instead of Value
  • (breaking change) INode::inner_text was moved to IHtmlElement::inner_text
  • (breaking change) Document::query_selector and Document::query_selector_all were moved to IParentNode
  • (breaking change) IElement::query_selector and IElement::query_selector_all were moved to IParentNode
  • (breaking change) Document::get_element_by_id was moved to INonElementParentNode
  • (breaking change) A blanket impl for converting between arbitrary reference-like objects using TryFrom/TryInto has been removed
  • When building using a recent cargo-web it's not necessary to call stdweb::initialize nor stdweb::event_loop anymore
  • Support for cdylib crates on wasm32-unknown-unknown
  • New bindings:
    • XmlHttpRequest
    • WebSocket
    • MutationObserver
    • History
    • TextAreaElement
    • CanvasElement
  • New event types:
    • MouseDownEvent
    • MouseUpEvent
    • MouseMoveEvent
    • PopStateEvent
    • ResizeEvent
    • ReadyStateChange
    • SocketCloseEvent
    • SocketErrorEvent
    • SocketOpenEvent
    • SocketMessageEvent
  • Initial support for the Canvas APIs
  • New traits: ReferenceType and InstanceOf
  • Add #[derive(ReferenceType)] in stdweb-derive crate; it's now possible to define custom API bindings outside of stdweb
  • Add #[js_export] procedural attribute (wasm32-unknown-unknown only)
  • Add DomException and subtypes for passing around JavaScript exceptions
  • IElement now inherits from INode
  • Every interface now inherits from ReferenceType
  • Add stdweb::traits module to act as a prelude for use-ing all of our interface traits
  • Add console! macro
  • Most types now implement PartialEq and Eq

• 0.3

  • (breaking change) Deleted ErrorEvent methods
  • (breaking change) Renamed:
    • LoadEvent -> ResourceLoadEvent
    • AbortEvent -> ResourceAbortEvent
    • ErrorEvent -> ResourceErrorEvent
  • Add UnsafeTypedArray for zero cost slice passing to js!
  • Add Once for passing FnOnce closures to js!

License

Licensed under either of

• Apache License, Version 2.0, (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Snippets of documentation which come from Mozilla Developer Network are covered under the CC-BY-SA, version 2.5 or later.

Contributing

See CONTRIBUTING.md