It's a bit between the two, really. There are typically still JavaScript helpers in the middle, but not for the reason most people think. The remaining reason is that Wasm cannot perform JavaScript method calls (with a receiver object). It can only perform function calls (without receiver). So you need JavaScript helpers in the middle to translate between a calling convention that doesn't use `this`, only regular parameters, to another convention where one of those parameters becomes the receiver of a method call.

Then that main reason has a number of declinations, like no JavaScript `new`, no field selection, etc. But you can work around all these things with similar "calling convention conversions".