Source Code: lib/tty.js
The node:tty module provides the tty.ReadStream and tty.WriteStream\nclasses. In most cases, it will not be necessary or possible to use this module\ndirectly. However, it can be accessed using:
node:tty
tty.ReadStream
tty.WriteStream
const tty = require('node:tty');\n
When Node.js detects that it is being run with a text terminal (\"TTY\")\nattached, process.stdin will, by default, be initialized as an instance of\ntty.ReadStream and both process.stdout and process.stderr will, by\ndefault, be instances of tty.WriteStream. The preferred method of determining\nwhether Node.js is being run within a TTY context is to check that the value of\nthe process.stdout.isTTY property is true:
process.stdin
process.stdout
process.stderr
process.stdout.isTTY
true
$ node -p -e \"Boolean(process.stdout.isTTY)\"\ntrue\n$ node -p -e \"Boolean(process.stdout.isTTY)\" | cat\nfalse\n
In most cases, there should be little to no reason for an application to\nmanually create instances of the tty.ReadStream and tty.WriteStream\nclasses.
Represents the readable side of a TTY. In normal circumstances\nprocess.stdin will be the only tty.ReadStream instance in a Node.js\nprocess and there should be no reason to create additional instances.
A boolean that is true if the TTY is currently configured to operate as a\nraw device. Defaults to false.
boolean
false
A boolean that is always true for tty.ReadStream instances.
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\nincluding modifiers. Additionally, all special processing of characters by the\nterminal is disabled, including echoing input\ncharacters. Ctrl+C will no longer cause a SIGINT when\nin this mode.
SIGINT
Represents the writable side of a TTY. In normal circumstances,\nprocess.stdout and process.stderr will be the only\ntty.WriteStream instances created for a Node.js process and there\nshould be no reason to create additional instances.
The 'resize' event is emitted whenever either of the writeStream.columns\nor writeStream.rows properties have changed. No arguments are passed to the\nlistener callback when called.
'resize'
writeStream.columns
writeStream.rows
process.stdout.on('resize', () => {\n console.log('screen size has changed!');\n console.log(`${process.stdout.columns}x${process.stdout.rows}`);\n});\n
writeStream.clearLine() clears the current line of this WriteStream in a\ndirection identified by dir.
writeStream.clearLine()
WriteStream
dir
writeStream.clearScreenDown() clears this WriteStream from the current\ncursor down.
writeStream.clearScreenDown()
writeStream.cursorTo() moves this WriteStream's cursor to the specified\nposition.
writeStream.cursorTo()
Returns:
1
4
8
24
Use this to determine what colors the terminal supports. Due to the nature of\ncolors in terminals it is possible to either have false positives or false\nnegatives. It depends on process information and the environment variables that\nmay lie about what terminal is used.\nIt is possible to pass in an env object to simulate the usage of a specific\nterminal. This can be useful to check how specific environment settings behave.
env
To enforce a specific color support, use one of the below environment settings.
FORCE_COLOR = 0
FORCE_COLOR = 1
FORCE_COLOR = 2
FORCE_COLOR = 3
Disabling color support is also possible by using the NO_COLOR and\nNODE_DISABLE_COLORS environment variables.
NO_COLOR
NODE_DISABLE_COLORS
writeStream.getWindowSize() returns the size of the TTY\ncorresponding to this WriteStream. The array is of the type\n[numColumns, numRows] where numColumns and numRows represent the number\nof columns and rows in the corresponding TTY.
writeStream.getWindowSize()
[numColumns, numRows]
numColumns
numRows
Returns true if the writeStream supports at least as many colors as provided\nin count. Minimum support is 2 (black and white).
writeStream
count
This has the same false positives and negatives as described in\nwriteStream.getColorDepth().
writeStream.getColorDepth()
process.stdout.hasColors();\n// Returns true or false depending on if `stdout` supports at least 16 colors.\nprocess.stdout.hasColors(256);\n// Returns true or false depending on if `stdout` supports at least 256 colors.\nprocess.stdout.hasColors({ TMUX: '1' });\n// Returns true.\nprocess.stdout.hasColors(2 ** 24, { TMUX: '1' });\n// Returns false (the environment setting pretends to support 2 ** 8 colors).\n
writeStream.moveCursor() moves this WriteStream's cursor relative to its\ncurrent position.
writeStream.moveCursor()
A number specifying the number of columns the TTY currently has. This property\nis updated whenever the 'resize' event is emitted.
number
A boolean that is always true.
A number specifying the number of rows the TTY currently has. This property\nis updated whenever the 'resize' event is emitted.
The tty.isatty() method returns true if the given fd is associated with\na TTY and false if it is not, including whenever fd is not a non-negative\ninteger.
tty.isatty()
fd