Skip to content

IoT.js-API-Stream.md

Latest commit

 

History

History
107 lines (57 loc) · 2.83 KB

IoT.js-API-Stream.md

File metadata and controls

107 lines (57 loc) · 2.83 KB

Class: Stream.Readable

Readable stream is abstraction for data source from which data will be read.

At any time a readable stream is in one of two state: flowing and paused. In paused state, readable stream emits 'readable' event for you that indicates there are data ready for read. and then you can explicitly call stream.read() to get the data form the stream. In flowing state, readable stream emits 'data' event with actual data that you can receive data as fast as possible. All streams start out in paused mode.

Events

'close'

  • callback: Function()

Emitted when the underlying resource has been closed.

'data'

  • callback: Function(chunk)
  • chunk: Buffer | String

Readable stream emits this event when a chunk of data prepared to be read. This event only emitted when the stream is in flowing state.

Attaching a data event listener to a stream makes the stream to be switched to flowing mode.

'end'

  • callback: Function()

This event is only fired when there will be no more data to read.

'readable'

  • callback: Function()

Readable stream emits this event when a chunk of data prepared to be read. This event only emitted when the stream is in paused state.

Methods

readable.isPaused()

Returns true if the readable stream is in paused mode.

readable.pause()

Pause emitting data events if the stream was in flowing mode

readable.read([size])

  • size | Number - specifies how much data will be read

Reads data from readable stream, and returns the data as String | Buffer

readable.resume()

Resume emitting data events if the readable was paused.

Class: stream.Writable

Writable stream is abstraction for target that you can write data to.

Events

'drain'

  • callback: Function()

If writable.write() returns false, drain events will indicate you that the stream is ready to be written.

'error'

  • callback: Function(err)
  • err: Error

Emitted if there were something wrong writing data.

'finish'

  • callback: Function()

After writable.end() has been called, and all data has been flushed, this event will be fired.

Methods

writable.end([chunk][, callback])

  • chunk: String | Buffer - The data to write
  • callback: Function() - Function callback for when the chunk of data is flushed.

writable.write(chunk[, callback])

  • chunk: String | Buffer - The data to write
  • callback: Function() - Function callback for when the chunk of data is flushed.
  • Returns: Boolean

This method writes chunk of data to the underlying system, when the data is flush it calls back the callback function. If you can write right after calling this method, it will return true, otherwise, return false.

Class: Stream.Duplex

Duplex streams are streams that implement both the Readable and Writable interfaces.