Print colored terminal output in Node.js

A terminal that understands ANSI styling can render text between a color sequence and a reset sequence. Node writes those characters; the terminal decides how to display them.

Use ANSI sequences

const red = '\x1b[31m';
const green = '\x1b[32m';
const reset = '\x1b[0m';

console.log(red + 'Operation failed' + reset);
console.log(green + 'Completed' + reset);

Reset the style after the message so later output does not inherit it.

Common style sequences include \x1b[1m for bold or increased intensity, \x1b[4m for underline, and \x1b[7m for inverse colors. You can combine them, for example \x1b[1m\x1b[33m for bold yellow. Appearance depends on the terminal and theme.

Use Chalk for readable styling

Install it with npm install chalk. Chalk 5 is an ES module package, so use an ES module such as colors.mjs:

import chalk from 'chalk';

console.log(chalk.red('Red text'));
console.log(chalk.green.bold('Bold green text'));
console.log(chalk.bgBlue.white('White text on blue'));

Chalk detects color support and normally disables styles for destinations without it. Explicit configuration or environment overrides can change that behavior, so “redirecting always removes colors” is too strong. Check package compatibility if your application uses older CommonJS tooling.

Keep redirected logs readable

A basic manual policy is to color only a terminal destination:

const message = 'Operation failed';
console.log(process.stdout.isTTY ? `\x1b[31m${message}\x1b[0m` : message);

isTTY is a useful signal, not a complete color-capability test. Respect your CLI's color preference and use a library's capability detection when you support many terminals. Escapes written to a file are control characters, not necessarily an encoding problem.

FAQ

Does this work on Windows? Modern Windows terminals commonly support ANSI styling, but behavior depends on the console host, configuration, and output destination. Test the terminals you support rather than relying on an operating-system version alone.

Should production logs be colored? Keep machine-consumed output plain or structured, usually JSON. Color can help an interactive console, while the file or collector output should remain easy to parse.

Why did later output change color too? The style was not reset, or a terminal interpreted a sequence differently. End each styled message deliberately and avoid injecting arbitrary terminal control characters from untrusted input.

References

• Chalk usage and color detection
• Node TTY API