the number of bytes that are currently buffered
the size of the buffer
Read data from the underlying source into the provided Uint8Array, up to the length of the array, and return the number of bytes read.
If there are no bytes available currently, the implementation is supposed to wait until at least one byte is available, and only then resolve the promise. Resolving the promise with a zero-length Uint8Array is marking the end of the source.
Uint8Array containing the bytes that were read.
A readable stream