After fetching some WebAssembly bytecode using fetch, we compile and instantiate the module using the WebAssembly.instantiateStreaming() function, importing a JavaScript function into the WebAssembly Module in the process. We then call an Exported WebAssembly function that is exported by the Instance.

const importObject = {
  imports: {
    imported_func(arg) {
      console.log(arg);
    },
  },
};

WebAssembly.instantiateStreaming(fetch('simple.wasm'), importObject)
  .then((obj) => obj.instance.exports.exported_func());

• WebAssembly overview page
• WebAssembly concepts
• Using the WebAssembly JavaScript API