You can use wasm-bridge without the component model, but not many features are implemented.

The provided API is identical to wasmtime's API, so read wasmtime's documentation on how to use this crate.

• Load a module from bytes or from WAT text
• Instantiate a module with or without imports
• Get typed or untyped exported function and call it
• Multivalue returns from exported and imported functions
• Supported value types: i32, i64, u32, u64, f32, f64
• Access store's data from Caller (imported fn)

See the no_bindgen test folder for supported example usages.

Here is an example of adding three using a WASM module compiled from WAT, using wasm-bridge version 0.3.0:

use wasm_bridge::*;

fn add_three(number: i32) -> Result<i32> {
    let mut store = Store::<()>::default();

    let wat = r#"
      (module
        (func $add_three (export "add_three")
          (param $p0 i32) (result i32)
          (i32.add (local.get $p0) (i32.const 3))
        )
      )
    "#;
    let module = Module::new(store.engine(), wat.as_bytes())?;

    let instance = Instance::new(&mut store, &module, &[])?;
    let add_three_wasm = instance.get_typed_func::<i32, i32>(&mut store, "add_three")?;

    let result = add_three_wasm.call(&mut store, number)?;
    Ok(result)
}

This example is very simple and uses the not recommended sync methods (see bellow). For a full example, see wbtutor-wasm-modules branch in the tutorials repo with nicely organized commits.

Alternatively, watch the video tutorial:

When running on the web, compiling and instantiation WASM modules syncly can result in an error.

Wasm-bridge provides async variants, which are safer to use and don't block the JS "thread" the code runs on.

These are, however, slightly different from the "normal" async functions that wasmtime provides, as described in this table:

The advantage of the "custom" wasm-bridge methods is that they work even without the async feature flag.