nodejs/doc/api/tty.markdown

TTY

Stability: 2 - Stable

The tty module houses the tty.ReadStream and tty.WriteStream classes. In most cases, you will not need to use this module directly.

When Node.js detects that it is being run inside a TTY context, then process.stdin will be a tty.ReadStream instance and process.stdout will be a tty.WriteStream instance. The preferred way to check if Node.js is being run in a TTY context is to check process.stdout.isTTY:

$ node -p -e "Boolean(process.stdout.isTTY)"
true
$ node -p -e "Boolean(process.stdout.isTTY)" | cat
false

Class: ReadStream

A net.Socket subclass that represents the readable portion of a tty. In normal circumstances, process.stdin will be the only tty.ReadStream instance in any Node.js program (only when isatty(0) is true).

rs.isRaw

A Boolean that is initialized to false. It represents the current "raw" state of the tty.ReadStream instance.

rs.setRawMode(mode)

mode should be true or false. This sets the properties of the tty.ReadStream to act either as a raw device or default. isRaw will be set to the resulting mode.

Class: WriteStream

A net.Socket subclass that represents the writable portion of a tty. In normal circumstances, process.stdout will be the only tty.WriteStream instance ever created (and only when isatty(1) is true).

Event: 'resize'

function () {}

Emitted by refreshSize() when either of the columns or rows properties has changed.

process.stdout.on('resize', () => {
  console.log('screen size has changed!');
  console.log(`${process.stdout.columns}x${process.stdout.rows}`);
});

ws.columns

A Number that gives the number of columns the TTY currently has. This property gets updated on 'resize' events.

ws.rows

A Number that gives the number of rows the TTY currently has. This property gets updated on 'resize' events.

tty.isatty(fd)

Returns true or false depending on if the fd is associated with a terminal.