WritableStream is part of the Streams API for creating, composing, and consuming streams of data. It is the writable counterpart to ReadableStream, which is already shipping in Chrome. It provides a standard abstraction for writing streaming data to a sink, with built-in backpressure and queuing. This is expected to be on by default in Chrome 59.
Docs: https://developer.mozilla.org/en-US/docs/Web/API/WritableStream