Gio.InputStream

const Gio = imports.gi.Gio;

let inputStream = new Gio.InputStream();
  

Gio.InputStream has functions to read from a stream (Gio.InputStream.prototype.read), to close a stream (Gio.InputStream.prototype.close) and to skip some content (Gio.InputStream.prototype.skip).

To copy the content of an input stream to an output stream without manually handling the reads and writes, use Gio.OutputStream.prototype.splice.

All of these functions have async variants too.