WebAssembly.compileStreaming()

source

A Response object or a promise that will fulfill with one, representing the underlying source of a Wasm module you want to stream and compile.

A Promise that resolves to a WebAssembly.Module object representing the compiled module.

• If source is not a Response or Promise resolving to a Response, the promise rejects with a TypeError.
• If compilation fails, the promise rejects with a WebAssembly.CompileError.
• If the source is a Promise that rejects, the promise rejects with the error.
• If the source's Result has an error (e.g. bad MIME type), the promise rejects with an error.

The following example (see our compile-streaming.html demo on GitHub, and view it live also) directly streams a Wasm module from an underlying source then compiles it to a WebAssembly.Module object. Because the compileStreaming() function accepts a promise for a Response object, you can directly pass it a Promise from calling fetch(), without waiting for the promise to fulfill.

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

WebAssembly.compileStreaming(fetch("simple.wasm"))
  .then((module) => WebAssembly.instantiate(module, importObject))
  .then((instance) => instance.exports.exported_func());

The resulting module instance is then instantiated using WebAssembly.instantiate(), and the exported function invoked.

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