if (offset = totalBytes) {
let messageMemoryView = new UInt8Array(。同城约会对此有专业解读
Configurable latency streaming。服务器推荐对此有专业解读
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.