terminal

Terminal output utilities for JavaScript libraries and CLIs. It provides small primitives for ANSI styles, color support detection, escape sequences, and testable stdout/stderr handling.

Features

ANSI Styles - Apply common modifiers, foreground colors, and background colors
Color Detection - Respect CI, NO_COLOR, FORCE_COLOR, TERM=dumb, TTY streams, and explicit style overrides
Terminal Controls - Generate escape sequences for cursor movement, line clearing, and cursor visibility
Testable Streams - Create terminal instances around injected stdout/stderr/stdin streams

Installation

npm i remix

Usage

import { createTerminal } from 'remix/terminal'

let terminal = createTerminal()

terminal.writeLine(`${terminal.styles.green('ready')} listening on port 3000`)
terminal.errorLine(terminal.styles.red('failed to start'))

ANSI Styles

Use createStyles when you only need formatting helpers.

import { createStyles } from 'remix/terminal'

let styles = createStyles({ colors: true })

console.log(styles.bold(styles.cyan('Ready')))
console.log(styles.format('warning', 'dim', 'yellow', 'bgBlackBright'))

Style helpers preserve outer styles when nested formatted strings close an inner style.

console.log(styles.red(`Error: ${styles.bold('fatal')} retrying`))

Supported modifiers include bold, dim, italic, underline, overline, inverse, and strikethrough. Supported colors include the base foreground/background ANSI colors, bright variants, and gray/grey aliases.

By default, color detection disables styles in CI, when NO_COLOR is present, for TERM=dumb, and outside TTY output streams. Set colors to true or false to override automatic detection.

Terminal Controls

Use ansi for raw terminal escape sequences.

import { ansi } from 'remix/terminal'

process.stdout.write(ansi.clearLine)
process.stdout.write(ansi.cursorTo(0))
process.stdout.write('Updated status')

Testing Output

Inject streams to test terminal output without writing to the real console.

import { createTerminal } from 'remix/terminal'

let output = ''

let terminal = createTerminal({
  colors: false,
  stdout: {
    write(chunk) {
      output += chunk
    },
  },
})

terminal.writeLine(terminal.styles.green('ok'))

Related Packages

logger-middleware - HTTP request/response logging middleware
test - Browser-based test framework for Remix components

License

See LICENSE