WebAssembly.compileStreaming()

The WebAssembly.compileStreaming() function compiles a WebAssembly.Module directly from a streamed underlying source. This function is useful if it is necessary to a compile a module before it can be instantiated (otherwise, the WebAssembly.instantiateStreaming() function should be used).

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 bufferSource is not a typed array, a TypeError is thrown.
• If compilation fails, the promise rejects with a WebAssembly.CompileError.

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 fetch() call, and it will pass the response into the function when it fulfills.

var importObject = { imports: { 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