readableStreamDefaultReader.read()

• 返回：用对象实现的 promise：

  ¥Returns: A promise fulfilled with an object:

  • value <ArrayBuffer>

  • done <boolean>

从底层 <ReadableStream> 请求下一个数据块，并返回一个 promise，一旦数据可用，该 promise 就会实现。

¥Requests the next chunk of data from the underlying <ReadableStream> and returns a promise that is fulfilled with the data once it is available.