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    A JavaScript ANSI color/style management. ANSI parsing. ANSI to CSS. Small, clean, no dependencies.

    npm install ansicolor

    What For

    • String coloring with ANSI escape codes
    • Solves the style hierarchy problem (when other similar tools fail)
    • Parsing/removing ANSI style data from strings
    • Converting ANSI styles to CSS or a Chrome DevTools-compatible output
    • A middleware for your platform-agnostic logging system

    Why Another One?

    Other tools lack consistency, failing to solve a simple hierarchy problem:

    require ('colors') // a popular color utility
    console.log (('foo'.cyan + 'bar').red)


    WTF?! The bar word above should be rendered in red, but it's not! That sucks. It's because ANSI codes are linear, not hierarchical (as with XML/HTML). A special kind of magic is needed to make this work. Ansicolor does that magic for you:

    require ('ansicolor').nice // .nice for unsafe String extensions
    console.log (('foo'.cyan + 'bar').red)



    Crash Course

    Importing (as methods):

    import { green, inverse, bgLightCyan, underline, dim } from 'ansicolor'
    const { green, inverse, bgLightCyan, underline, dim } = require ('ansicolor')


    console.log ('foo' + green (inverse (bgLightCyan ('bar')) + 'baz') + 'qux')
    console.log ( ('foo' + ('bar'))) // method chaining

    Importing (as object):

    import { ansicolor, ParsedSpan } from 'ansicolor' // along with type definitions
    import ansicolor from 'ansicolor'

    Nice Mode (not recommended)

    const ansi = require ('ansicolor').nice

    The ('ansicolor').nice export defines styling APIs on the String prototype directly. It uses an ad-hoc DSL (sort of) for infix-style string coloring. The nice is convenient, but not safe, avoid using it in public modules, as it alters global objects, and that might cause potential hard-to-debug compatibility issues.

    console.log ('foo'.red.bright + 'bar'.bgYellow.underline.dim)

    Supported Styles

    'foreground colors'
    'light foreground colors'
    'background colors'
    'light background colors'
        .bright.dim.italic.underline.inverse // your platform should support italic

    You also can obtain all those style names (for reflection purposes):

    const { names } = require ('ansicolor')
    names // ['red', 'green', ...

    Removing ANSI Styles From Strings

    const { strip } = require ('ansicolor')
    strip ('\u001b[0m\u001b[4m\u001b[42m\u001b[31mfoo\u001b[39m\u001b[49m\u001b[24mfoo\u001b[0m')) // 'foofoo'

    Checking If Strings Contain ANSI Codes

    const { isEscaped, green } = require ('ansicolor')
    isEscaped ('text')         // false
    isEscaped (green ('text')) // true

    Converting to CSS/HTML

    Inspection of ANSI styles in arbitrary strings is essential when implementing platform-agnostic logging — that piece of code is available under command line interface and in a browser as well. Here's an example of how you would parse a colored string into an array-like structure. That structure can be traversed later to build HTML/JSON/XML or any other markup/syntax.

    const { parse } = require ('ansicolor')
    const parsed = parse ('foo'.bgLightRed.bright.italic + 'bar'.red.dim)

    The ansi.parse () method will return a pseudo-array of styled spans, you can iterate over it with a for ... of loop and convert it to an array with the spread operator (...). Also, there's the .spans property for obtaining the already-spread array directly:

    assert.deepEqual (parsed.spans /* or [...parsed] */,
        [ { css: 'font-weight: bold;font-style: italic;background:rgba(255,51,0,1);',
            italic: true,
            bold: true,
            color: { bright: true },
            bgColor: { name: 'lightRed' },
            text: 'foo' },
          { css: 'color:rgba(204,0,0,0.5);',
            color: { name: 'red', dim: true },
            text: 'bar' } ])

    Custom Color Themes

    You can change default RGB values (won't work in terminals, affects only the ANSI→CSS transformation part):

    const ansi = require ('ansicolor')
    ansi.rgb = {
        black:        [0,     0,   0],    
        darkGray:     [100, 100, 100],
        lightGray:    [200, 200, 200],
        white:        [255, 255, 255],
        red:          [204,   0,   0],
        lightRed:     [255,  51,   0],
        green:        [0,   204,   0],
        lightGreen:   [51,  204,  51],
        yellow:       [204, 102,   0],
        lightYellow:  [255, 153,  51],
        blue:         [0,     0, 255],
        lightBlue:    [26,  140, 255],
        magenta:      [204,   0, 204],
        lightMagenta: [255,   0, 255],
        cyan:         [0,   153, 255],
        lightCyan:    [0,   204, 255],

    Chrome DevTools Compatibility

    Web browsers usually implement their own proprietary CSS-based color formats for console.log and most of them fail to display standard ANSI colors. Ansicolor offers you a helper method to convert ANSI-styled strings to browser-compatible argument lists acceptable by Chrome's console.log:

    const { bgGreen, red, parse } = require ('ansicolor')
    const string = 'foo' + bgGreen (red.underline.bright.inverse ('bar') + 'baz')
    const parsed = parse (string)
    console.log (...parsed.asChromeConsoleLogArguments) // prints with colors in Chrome!

    Here's what the format looks like:

    parsed.asChromeConsoleLogArguments // [ "%cfoo%cbar%cbaz",
                                       //   "",
                                       //   "font-weight: bold;text-decoration: underline;background:rgba(255,51,0,1);color:rgba(0,204,0,1);",
                                       //   "background:rgba(0,204,0,1);"
                                       // ]

    Play with this feature online: demo page. Open the DevTools console and type expressions in the input box to see colored console output.

    Happy logging!

    Projects That Use ansicolor

    • Ololog! — a better console.log for the log-driven debugging junkies
    • CCXT — a cryptocurrency trading API with 130+ exchanges
    • Grafana — beautiful monitoring & metric analytics & dashboards


    npm i ansicolor

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