The Writer is not a concrete class. Any object that implements write(), end(), and abort() can be a writer making it easy to adapt existing APIs or create specialized implementations without subclassing. There's no complex UnderlyingSink protocol with start(), write(), close(), and abort() callbacks that must coordinate through a controller whose lifecycle and state are independent of the WritableStream it is bound to.
WebAssembly with no kernel at allWebAssembly takes a fundamentally different approach. Instead of running native code and filtering its kernel access, WASM runs code in a memory-safe virtual machine that has no syscall interface at all. All interaction with the host happens through explicitly imported host functions.，这一点在同城约会中也有详细论述
，这一点在safew官方版本下载中也有详细论述
Async iteration (8KB × 1000)
FT Digital Edition: our digitised print edition。爱思助手下载最新版本对此有专业解读