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Node.js v8.8.0 Documentation
Table of Contents
TTY#
The tty module provides the tty.ReadStream and tty.WriteStream classes.
In most cases, it will not be necessary or possible to use this module directly.
However, it can be accessed using:
const tty = require('tty');
When Node.js detects that it is being run inside a text terminal ("TTY")
context, the process.stdin will, by default, be initialized as an instance of
tty.ReadStream and both process.stdout and process.stderr will, by
default be instances of tty.WriteStream. The preferred method of determining
whether Node.js is being run within a TTY context is to check that the value of
the process.stdout.isTTY property is true:
$ node -p -e "Boolean(process.stdout.isTTY)"
true
$ node -p -e "Boolean(process.stdout.isTTY)" | cat
false
In most cases, there should be little to no reason for an application to
create instances of the tty.ReadStream and tty.WriteStream classes.
Class: tty.ReadStream#
The tty.ReadStream class is a subclass of net.Socket that represents the
readable side of a TTY. In normal circumstances process.stdin will be the
only tty.ReadStream instance in a Node.js process and there should be no
reason to create additional instances.
readStream.isRaw#
A boolean that is true if the TTY is currently configured to operate as a
raw device. Defaults to false.
readStream.setRawMode(mode)#
Allows configuration of tty.ReadStream so that it operates as a raw device.
When in raw mode, input is always available character-by-character, not
including modifiers. Additionally, all special processing of characters by the
terminal is disabled, including echoing input characters.
Note that CTRL+C will no longer cause a SIGINT when in this mode.
mode<boolean> Iftrue, configures thetty.ReadStreamto operate as a raw device. Iffalse, configures thetty.ReadStreamto operate in its default mode. ThereadStream.isRawproperty will be set to the resulting mode.
Class: tty.WriteStream#
The tty.WriteStream class is a subclass of net.Socket that represents the
writable side of a TTY. In normal circumstances, process.stdout and
process.stderr will be the only tty.WriteStream instances created for a
Node.js process and there should be no reason to create additional instances.
Event: 'resize'#
The 'resize' event is emitted whenever either of the writeStream.columns
or writeStream.rows properties have changed. No arguments are passed to the
listener callback when called.
process.stdout.on('resize', () => {
console.log('screen size has changed!');
console.log(`${process.stdout.columns}x${process.stdout.rows}`);
});
Note: On Windows resize events will be emitted only if stdin is unpaused
(by a call to resume() or by adding a data listener) and in raw mode. It can
also be triggered if a terminal control sequence that moves the cursor is
written to the screen. Also, the resize event will only be signaled if the
console screen buffer height was also changed. For example shrinking the
console window height will not cause the resize event to be emitted. Increasing
the console window height will only be registered when the new console window
height is greater than the current console buffer size.
writeStream.columns#
A number specifying the number of columns the TTY currently has. This property
is updated whenever the 'resize' event is emitted.
writeStream.rows#
A number specifying the number of rows the TTY currently has. This property
is updated whenever the 'resize' event is emitted.
tty.isatty(fd)#
fd<number> A numeric file descriptor
The tty.isatty() method returns true if the given fd is associated with
a TTY and false if it is not, including whenever fd is not a non-negative
integer.