stream.read()

stream.read(0)

There are some cases where you want to trigger a refresh of the underlying readable stream mechanisms, without actually consuming any data. In that case, you can call stream.read(0), which will always return null.

If the internal read buffer is below the highWaterMark, and the stream is not currently reading, then calling stream.read(0) will trigger a low-level stream._read() call.

There is almost never a need to do this. However, you will see some cases in Node.js's internals where this is done, particularly in the Readable stream class internals.