Any non-toy WASM application running in browsers will almost certainly end up as a hybrid WASM/JS application, just because you can't call directly from WASM into browser APIs, and even if the JS shim is "hidden from view", sometimes it's either more convenient or even more performant to write more than just a thin API shim in Javascript, especially for asynchronous code or to avoid redundant copying of large data blobs in and out of the WASM heap.