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Node.js v12.0.0-rc.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.ReadStream
to operate as a raw device. Iffalse
, configures thetty.ReadStream
to operate in its default mode. ThereadStream.isRaw
property 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. This enables simulating the usage of a specific terminal. Default:process.env
.- Returns: <number>
Returns:
1
for 2,4
for 16,8
for 256,24
for 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.
It is possible to pass in an env
object to simulate the usage of a specific
terminal. This can be useful to check how specific environment settings behave.
To enforce a specific color support, use one of the below environment settings.
- 2 colors:
FORCE_COLOR = 0
(Disables colors) - 16 colors:
FORCE_COLOR = 1
- 256 colors:
FORCE_COLOR = 2
- 16,777,216 colors:
FORCE_COLOR = 3
Disabling color support is also possible by using the NO_COLOR
and
NODE_DISABLE_COLORS
environment variables.
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]#
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.