@visulima/is-ansi-color-supported

Visulima is-ansi-color-supported

Detect whether a terminal (stdout/stderr), browser or edge supports (next.js) ansi colors.

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^{Daniel Bannert's open source work is supported by the community on GitHub Sponsors}

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Install

npm install @visulima/is-ansi-color-supported

yarn add @visulima/is-ansi-color-supported

pnpm add @visulima/is-ansi-color-supported

Usage

import { isStdoutColorSupported, isStderrColorSupported } from "@visulima/is-ansi-color-supported";

/**
 * Levels:
 * - `0` - All colors disabled.
 * - `1` - Basic 16 colors support.
 * - `2` - ANSI 256 colors support.
 * - `3` - Truecolor 16 million colors support.
 */
console.log(isStdoutColorSupported()); // 3

console.log(isStderrColorSupported()); // 3

Color support

Ansis automatically detects the supported color space:

• TrueColor
• ANSI 256 colors
• ANSI 16 colors
• black & white (no color)

There is no standard way to detect which color space is supported. The most common way to detect color support is to check the TERM and COLORTERM environment variables. CI systems can be detected by checking for the existence of the CI and other specifically environment variables. Combine that with the knowledge about which operating system the program is running on, and we have a decent enough way to detect colors.

Terminal	ANSI 16 colors	ANSI 256 colors	True Color	env. TERM	env. COLORTERM	Specifically ENV variables
Azure CI	✅	❌	❌	dumb		TF_BUILD AGENT_NAME
GitHub CI	✅	✅	✅	dumb		CI GITHUB_ACTIONS
GitTea CI	✅	✅	✅	dumb		CI GITEA_ACTIONS
GitLab CI	✅	❌	❌	dumb		CI GITLAB_CI
Travis CI	✅	❌	❌	dumb		TRAVIS
PM2 not isTTY	✅1	✅1	✅1	dumb		PM2_HOME pm_id
JetBrains TeamCity >=2020.1.1	✅	✅	❌			TEAMCITY_VERSION
JetBrains IDEA	✅	✅	✅	xterm-256color		TERMINAL_EMULATOR='JetBrains-JediTerm'
VS Code	✅	✅	✅	xterm-256color	truecolor
Windows Terminal	✅	✅	✅2
Windows PowerShell	✅	✅	✅2
macOS Terminal	✅	✅	❌	xterm-256color
iTerm	✅	✅	✅	xterm-256color	truecolor
Terminal emulator Kitty	✅	✅	✅	xterm-kitty

See also:

• Truecolor Support in Output Devices.
• So you want to render colors in your terminal.

Environment variables

To force disable or enable colored output use environment variables NO_COLOR and FORCE_COLOR.

The NO_COLOR variable should be presents with any not empty value. The value is not important, e.g., NO_COLOR=1 NO_COLOR=true disable colors. See standard description by NO_COLOR.

The FORCE_COLOR variable should be presents with one of values:
FORCE_COLOR=0 force disable colors
FORCE_COLOR=1 force enable colors

CLI arguments

Use arguments --no-color or --color=false to disable colors and --color to enable ones.

For example, an executable script colors.js:

#!/usr/bin/env node
import { isStdoutColorSupported } from "@visulima/is-ansi-color-supported";

console.log(isStdoutColorSupported());

Execute the script in a terminal:

$ ./colors.js                        # colored output in terminal
$ ./colors.js --no-color             # non colored output in terminal
$ ./colors.js --color=false          # non colored output in terminal

$ ./colors.js > log.txt              # output in file without ANSI codes
$ ./colors.js --color > log.txt      # output in file with ANSI codes
$ ./colors.js --color=true > log.txt # output in file with ANSI codes

Warning

The command line arguments have a higher priority than environment variable.

Info

For situations where using --color is not possible, use the environment variable FORCE_COLOR=1 (level 1), FORCE_COLOR=2 (level 2), or FORCE_COLOR=3 (level 3) to forcefully enable color, or FORCE_COLOR=0 to forcefully disable. The use of FORCE_COLOR overrides all other color support checks.

Explicit 256/Truecolor mode can be enabled using the --color=256 and --color=16m flags, respectively.

Related

• supports-color - Detect whether a terminal supports color
• supports-color-cli - CLI for this module

Supported Node.js Versions

Libraries in this ecosystem make the best effort to track Node.js’ release schedule. Here’s a post on why we think this is important.

Contributing

If you would like to help take a look at the list of issues and check our Contributing guild.

Note: please note that this project is released with a Contributor Code of Conduct. By participating in this project you agree to abide by its terms.

Credits

• Daniel Bannert
• All Contributors

License

The visulima is-ansi-color-supported is open-sourced software licensed under the MIT

Footnotes

1. Colors supported depends on actual terminal. ↩ ↩² ↩³

2. The Windows terminal supports true color since Windows 10 revision 14931 (2016-09-21). ↩ ↩²