@tduyng/prettyoutput

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

Features

• Fast: 2–3x faster than util.inspect
• Configurable: colors, depth, indentation, etc.
• Cross-platform: Node.js, Deno, Bun, and CLI
• ESM and CommonJS support
• TypeScript-first, with full type safety
• Zero dependencies
• Tested with high coverage

Let me know if you want a shorter or more opinionated tone (e.g., for dev-focused landing pages).

Installation

npm  add @tduyng/prettyoutput
yarn add @tduyng/prettyoutput
pnpm add @tduyng/prettyoutput

Usage

@tduyng/prettyoutput is extremely easy to use. Just require it in your project and call the function with your data:

import { prettyOutput } from '@tduyng/prettyoutput'

const data = {
    username: 'tduyng',
    url: 'https://github.com/tduyng',
    projects: ['@tduyng/prettyoutput', '@tduyng/logger'],
}

console.log(prettyOutput(data))

Sample output:

username: tduyng
url: https://github.com/tduyng
projects:
  - @tduyng/prettyoutput
  - @tduyng/logger

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 '@tduyng/prettyoutput'

const data = {
    username: 'tduyng',
    url: 'https://github.com/tduyng',
    projects: ['@tduyng/prettyoutput', '@tduyng/logger'],
}

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

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

CLI Usage

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

Available Aliases

There are multiple aliases available for the CLI, allowing you to use the command that best fits your workflow:

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

# Pretty print a JSON file
prettyoutput package.json       # for ESM
pretty package.json             # for ESM
prettyoutput-cjs package.json   # for CJS
pretty-cjs 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 prettyoutput is built to be fast. Compared to alternatives like util.inspect and prettyjson, it consistently performs 2x-3x times faster.

Run Benchmarks

pnpm run benchmark

Benchmark Results

Tested on Node.js 24.8.0

LEVELS | KEYS | LOOPS | WEIGHTS
1      | 20   | 100   | serializable: 0.9    array: 0.3    object: 0.5    multilineString: 0.3    error: 0.2

NAME             | MIN        | MAX           | MEAN       | TOTAL
prettyoutput     | 6µs 834ns  | 2ms 8µs 875ns | 36µs 267ns | 3ms 626µs 709ns
prettyjson       | 13µs 792ns | 344µs 875ns   | 26µs 445ns | 2ms 644µs 583ns
util.inspect     | 10µs 875ns | 150µs 375ns   | 16µs 815ns | 1ms 681µs 588ns
@poppinss/dumper | 43µs 209ns | 961µs 959ns   | 76µs 326ns | 7ms 632µs 670ns
--------------------------------------------------------------------------------------------------------------


LEVELS | KEYS | LOOPS | WEIGHTS
2      | 20   | 100   | serializable: 0.9    array: 0.3    object: 0.5    multilineString: 0.3    error: 0.2

NAME             | MIN         | MAX         | MEAN        | TOTAL
prettyoutput     | 27µs 875ns  | 454µs 83ns  | 42µs 807ns  | 4ms 280µs 793ns
prettyjson       | 58µs 583ns  | 163µs 541ns | 73µs 734ns  | 7ms 373µs 456ns
util.inspect     | 101µs 625ns | 583µs 542ns | 123µs 526ns | 12ms 352µs 668ns
@poppinss/dumper | 171µs 458ns | 510µs 250ns | 207µs 106ns | 20ms 710µs 623ns
--------------------------------------------------------------------------------------------------------------


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
prettyoutput     | 346µs 875ns     | 3ms 814µs 709ns | 460µs 657ns     | 46ms 65µs 759ns
prettyjson       | 807µs 750ns     | 1ms 256µs 667ns | 899µs 45ns      | 89ms 904µs 586ns
util.inspect     | 1ms 419µs 625ns | 1ms 874µs 375ns | 1ms 532µs 755ns | 153ms 275µs 587ns
@poppinss/dumper | 2ms 640µs 584ns | 3ms 596µs 666ns | 2ms 954µs 927ns | 295ms 492µs 722ns
--------------------------------------------------------------------------------------------------------------


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
prettyoutput     | 3ms 593µs 333ns  | 28ms 998µs 208ns | 4ms 444µs 335ns  | 444ms 433µs 545ns
prettyjson       | 6ms 779µs 125ns  | 8ms 323µs 292ns  | 7ms 344µs 228ns  | 734ms 422µs 834ns
util.inspect     | 13ms 944µs 666ns | 23ms 601µs 458ns | 15ms 140µs 162ns | 1s 514ms 16µs 206ns
@poppinss/dumper | 31ms 645µs 458ns | 44ms 678µs 500ns | 35ms 198µs 832ns | 3s 519ms 883µs 256ns
--------------------------------------------------------------------------------------------------------------


LEVELS | KEYS | LOOPS | WEIGHTS
4      | 20   | 200   | serializable: 0.9    array: 0.3    object: 0.5    multilineString: 0.3    error: 0.2

NAME             | MIN              | MAX              | MEAN             | TOTAL
prettyoutput     | 2ms 472µs 375ns  | 19ms 756µs 416ns | 2ms 841µs 423ns  | 568ms 284µs 792ns
prettyjson       | 3ms 983µs 584ns  | 5ms 516µs 375ns  | 4ms 419µs 219ns  | 883ms 843µs 868ns
util.inspect     | 14ms 861µs 417ns | 23ms 170µs 792ns | 16ms 48µs 375ns  | 3s 209ms 675µs 126ns
@poppinss/dumper | 20ms 774µs 625ns | 28ms 990µs 41ns  | 23ms 617µs 484ns | 4s 723ms 496µs 967ns
--------------------------------------------------------------------------------------------------------------


LEVELS | KEYS | LOOPS | WEIGHTS
5      | 10   | 100   | serializable: 0.9    array: 0.3    object: 0.5    multilineString: 0.3    error: 0.2

NAME             | MIN             | MAX             | MEAN            | TOTAL
prettyoutput     | 540µs 542ns     | 3ms 999µs 667ns | 644µs 326ns     | 64ms 432µs 622ns
prettyjson       | 968µs 0ns       | 1ms 804µs 625ns | 1ms 105µs 952ns | 110ms 595µs 295ns
util.inspect     | 2ms 859µs 959ns | 3ms 856µs 541ns | 3ms 128µs 76ns  | 312ms 807µs 666ns
@poppinss/dumper | 4ms 281µs 167ns | 5ms 567µs 291ns | 4ms 708µs 354ns | 470ms 835µs 455ns
--------------------------------------------------------------------------------------------------------------

For detailed benchmark results, refer to the benchmark documentation.

Testing

Clone the repository and install development dependencies:

pnpm install

Run tests:

pnpm run test
# or pnpm run coverage

Contribution

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

Credits

@tduyng/prettyoutput 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.