pretty-output

pretty-output is a fast, customizable library for formatting JavaScript/JSON objects into a human-readable, YAML-style output.

Features

• High Performance: Optimized to be 1.x-3.x times faster and more beautiful than util.inspect, making it ideal for real-time logging.
• Customizable: Configure indentation, color schemes, depth limits, and more to fit your specific needs.
• Versatile: Works as both a Node.js, Deno, Bun library and a CLI tool, giving flexibility for scripts and terminal usage.
• Color Output: Easily distinguish keys, strings, numbers, and more with customizable color formatting.
• Dual Package: Supports both ES modules and CommonJS, ensuring compatibility with various JavaScript environments.
• TypeScript Support: Fully written in TypeScript, offering type safety and modern development practices.
• Simple and Tested: Designed for ease of use with a thoroughly tested codebase.
• Zero Dependencies: Uses only commander.js for the CLI.

Installation

npm add pretty-output
yarn add pretty-output
pnpm add pretty-output

Usage

pretty-output is extremely easy to use. Just require it in your project and call the function with your data:

import { prettyOutput } from 'pretty-output'

const data = {
  username: 'kic',
  url: 'https://github.com/keepitcool',
  projects: ['prettyoutput', '3m2tuio']
}

console.log(prettyOutput(data))

Sample output:

username: kic
url: https://github.com/keepitcool
projects:
  - pretty-output
  - 3m2tuio

Other example:

API

prettyOutput(data, options, indent)

Parameters

 * {*} data                     : The JavaScript or JSON object to format
 * {Object} [options]           : Optional. See options below
 * {number} [indent]            : Optional. Indent all output

Options

 * {number} [indentationLength] : Length of indentation (in terms of space)
 * {number} [maxDepth]          : maximum sublevel of nested objects/arrays output. Default: 3
 * {boolean}[noColor]           : disable colors. Default: false
 * {colors} [colors]            : Output colors. See below
 * {boolean}[alignKeyValues]    : Align key values. Default: true
 * {boolean}[hideUndefined]     : Do not display undefined values. Default: false

Colors Options

 * {string} [keys]              : Objects keys color. Default: green
 * {string} [dash]              : Array prefixing dash ("- "). Default: green
 * {string} [number]            : Numbers color. Default: blue
 * {string} [string]            : Strings color. Default: no color
 * {string} [true]              : Boolean value 'true' color. Default: green
 * {string} [false]             : Boolean value 'false' color. Default: red
 * {string} [null]              : 'Null' color. Default: grey
 * {string} [undefined]         : 'Undefined' color. Default: grey

Example using options :

import { prettyOutput } from 'pretty-output'

const data = {
  username: 'kic',
  url: 'https://github.com/keepitcool',
  projects: ['pretty-output', '3m2tuio']
};

const options = {
  noColor: true,
  maxDepth: 5,
  colors: {
    keys: 'blue',
    null: 'red'
  }
};

console.log(prettyOutput(data, options, 2));

CLI Usage

You can also use pretty-output directly from the command line to format files or standard input.

Usage:

# Pretty print a JSON file
prettyoutput package.json       # for ESM
pretty package.json             # for ESM
prettyoutput-esm package.json   # for ESM
pretty-esm package.json         # for ESM
prettyoutput-cjs package.json   # for CJS
pretty package.json             # for CJS

Example CLI Output:

Command Line Options

• --indent: Set the indentation level (default: 2).
• --depth: Limit the depth of object printing (default: 3).
• --noColor: Disable colored output.

# Format with custom indentation, depth, and no color
prettyoutput --indent=4 --depth=5 --noColor package.json

or

# Indent 4, max depth 5, disable colors
cat package.json | prettyoutput --indent=4 --depth=5 --noColor

Benchmark

Performance is key for logging, and pretty-output is built to be fast. Compared to alternatives like util.inspect and prettyjson, it consistently performs 1.x-3.x times faster.

Run Benchmarks

node benchmark/benchmark.js

Benchmark Results

Tested on Node.js 22.8.0

LEVELS | KEYS | LOOPS | WEIGHTS
3      | 20   | 100   | serializable: 0.9    array: 0.3    object: 0.5    multilineString: 0.3    error: 0.2

NAME             | MIN                 | MAX                 | MEAN                | TOTAL
pretty-output    | 1 ms 417 µs 200 ns  | 35 ms 930 µs 467 ns | 2 ms 5 µs 439 ns    | 200 ms 543 µs 970 ns
prettyjson       | 4 ms 56 µs 696 ns   | 9 ms 317 µs 632 ns  | 4 ms 473 µs 214 ns  | 447 ms 321 µs 437 ns
util.inspect     | 3 ms 895 µs 505 ns  | 12 ms 743 µs 60 ns  | 4 ms 463 µs 826 ns  | 446 ms 382 µs 620 ns
@poppinss/dumper | 12 ms 185 µs 629 ns | 24 ms 81 µs 159 ns  | 14 ms 167 µs 609 ns | 1 s 416 ms 760 µs 966 ns
--------------------------------------------------------------------------------------------------------------


LEVELS | KEYS | LOOPS | WEIGHTS
4      | 20   | 100   | serializable: 0.9    array: 0.3    object: 0.5    multilineString: 0.3    error: 0.2

NAME             | MIN                 | MAX                  | MEAN                | TOTAL
pretty-output    | 7 ms 741 µs 194 ns  | 118 ms 124 µs 145 ns | 11 ms 263 µs 170 ns | 1 s 126 ms 317 µs 3 ns
prettyjson       | 18 ms 281 µs 941 ns | 28 ms 144 µs 657 ns  | 19 ms 861 µs 800 ns | 1 s 986 ms 180 µs 75 ns
util.inspect     | 28 ms 601 µs 804 ns | 57 ms 71 µs 136 ns   | 31 ms 647 µs 947 ns | 3 s 164 ms 794 µs 787 ns
@poppinss/dumper | 61 ms 791 µs 290 ns | 94 ms 660 µs 42 ns   | 69 ms 241 µs 879 ns | 6 s 924 ms 187 µs 908 ns
--------------------------------------------------------------------------------------------------------------


LEVELS | KEYS | LOOPS | WEIGHTS
4      | 40   | 200   | serializable: 0.9    array: 0.3    object: 0.5    multilineString: 0.3    error: 0.2

NAME             | MIN                     | MAX                      | MEAN                     | TOTAL
pretty-output    | 322 ms 378 µs 833 ns    | 2 s 470 ms 343 µs 997 ns | 408 ms 177 µs 619 ns     | 81 s 635 ms 523 µs 870 ns
prettyjson       | 413 ms 885 µs 631 ns    | 949 ms 765 µs 323 ns     | 498 ms 554 µs 581 ns     | 99 s 710 ms 916 µs 350 ns
util.inspect     | 728 ms 839 µs 615 ns    | 1 s 938 ms 281 µs 319 ns | 838 ms 188 µs 569 ns     | 167 s 637 ms 713 µs 859 ns
@poppinss/dumper | 1 s 389 ms 498 µs 39 ns | 2 s 445 ms 781 µs 141 ns | 1 s 634 ms 909 µs 384 ns | 326 s 981 ms 876 µs 857 ns
--------------------------------------------------------------------------------------------------------------


LEVELS | KEYS | LOOPS | WEIGHTS
5      | 20   | 100   | serializable: 0.9    array: 0.3    object: 0.5    multilineString: 0.3    error: 0.2

NAME             | MIN                  | MAX                      | MEAN                    | TOTAL
pretty-output    | 201 ms 29 µs 587 ns  | 1 s 651 ms 200 µs 25 ns  | 245 ms 777 µs 771 ns    | 24 s 577 ms 777 µs 190 ns
prettyjson       | 229 ms 631 µs 36 ns  | 467 ms 527 µs 984 ns     | 269 ms 62 µs 662 ns     | 26 s 906 ms 266 µs 294 ns
util.inspect     | 828 ms 156 µs 412 ns | 1 s 884 ms 775 µs 777 ns | 920 ms 237 µs 642 ns    | 92 s 23 ms 764 µs 261 ns
@poppinss/dumper | 889 ms 54 µs 772 ns  | 1 s 323 ms 199 µs 230 ns | 1 s 14 ms 384 µs 206 ns | 101 s 438 ms 420 µs 665 ns
--------------------------------------------------------------------------------------------------------------

Testing

Clone the repository and install development dependencies:

yarn install

Run tests:

yarn test

Contribution

If you'd like to contribute to this project, feel free to submit issues and pull requests. Contributions are always welcome!

Credits

pretty-output is based on the original prettyoutput project, which is now archived. Special thanks to @bnadim for creating the original project, and to all contributors who helped enhance it over time.