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Node.js v10.23.2 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 with a text terminal ("TTY")
attached, 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
manually create instances of the tty.ReadStream and tty.WriteStream
classes.
Class: tty.ReadStream[src]#
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.isTTY#
A boolean that is always true for tty.ReadStream instances.
readStream.setRawMode(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.- Returns: <this> - the read stream instance.
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.
Class: tty.WriteStream[src]#
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}`);
});
writeStream.clearLine(dir)#
-
dir<number>-1- to the left from cursor1- to the right from cursor0- the entire line
writeStream.clearLine() clears the current line of this WriteStream in a
direction identified by dir.
writeStream.clearScreenDown()#
writeStream.clearScreenDown() clears this WriteStream from the current
cursor down.
writeStream.columns#
A number specifying the number of columns the TTY currently has. This property
is updated whenever the 'resize' event is emitted.
writeStream.cursorTo(x, y)#
writeStream.cursorTo() moves this WriteStream's cursor to the specified
position.
writeStream.getColorDepth([env])#
env<Object> An object containing the environment variables to check. Default:process.env.- Returns: <number>
Returns:
1for 2,4for 16,8for 256,24for 16,777,216 colors supported.
Use this to determine what colors the terminal supports. Due to the nature of
colors in terminals it is possible to either have false positives or false
negatives. It depends on process information and the environment variables that
may lie about what terminal is used.
To enforce a specific behavior without relying on process.env it is possible
to pass in an object with different settings.
Use the NODE_DISABLE_COLORS environment variable to enforce this function to
always return 1.
writeStream.getWindowSize()#
- Returns: <number[]>
writeStream.getWindowSize() returns the size of the TTY
corresponding to this WriteStream. The array is of the type
[numColumns, numRows] where numColumns and numRows represent the number
of columns and rows in the corresponding TTY.
writeStream.hasColors([count][, env])#
count<integer> The number of colors that are requested (minimum 2). Default: 16.env<Object> An object containing the environment variables to check. This enables simulating the usage of a specific terminal. Default:process.env.- Returns: <boolean>
Returns true if the writeStream supports at least as many colors as provided
in count. Minimum support is 2 (black and white).
This has the same false positives and negatives as described in
writeStream.getColorDepth().
process.stdout.hasColors();
// Returns true or false depending on if `stdout` supports at least 16 colors.
process.stdout.hasColors(256);
// Returns true or false depending on if `stdout` supports at least 256 colors.
process.stdout.hasColors({ TMUX: '1' });
// Returns true.
process.stdout.hasColors(2 ** 24, { TMUX: '1' });
// Returns false (the environment setting pretends to support 2 ** 8 colors).
writeStream.isTTY#
A boolean that is always true.
writeStream.moveCursor(dx, dy)#
writeStream.moveCursor() moves this WriteStream's cursor relative to its
current position.
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)[src]#
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.