wasmer/lib/js-api

wasmer-js

Wasmer is the most popular WebAssembly runtime for Rust (...and also the fastest). This runtime is an adapted version of the Wasmer API that compiles to WebAssembly via wasm-bindgen.

wasmer-js uses the same WebAssembly runtime of your environment (browser or Node.js).

Usage

use wasmer_js::{Store, Module, Instance, Value, imports};

fn main() -> anyhow::Result<()> {
    let module_wat = r#"
    (module
    (type $t0 (func (param i32) (result i32)))
    (func $add_one (export "add_one") (type $t0) (param $p0 i32) (result i32)
        get_local $p0
        i32.const 1
        i32.add))
    "#;

    let store = Store::default();
    let module = Module::new(&store, &module_wat)?;
    // The module doesn't import anything, so we create an empty import object.
    let import_object = imports! {};
    let instance = Instance::new(&module, &import_object)?;

    let add_one = instance.exports.get_function("add_one")?;
    let result = add_one.call(&[Value::I32(42)])?;
    assert_eq!(result[0], Value::I32(43));

    Ok(())
}

Config flags

Wasmer has the following configuration flags:

• wat (enabled by default): It allows to read WebAssembly files in their text format. This feature is normally used only in development environments

Build

You can use wasm-pack to build wasmer-js:

wasm-pack build --release

The provided wasmer_js.wasm file should weight around 75kB when optmized via wasm-opt and stripped via wasm-strip, so it's relatively slim.

Test

wasm-pack test --node

---

Made with ❤️ by the Wasmer team, for the community