@tduyng/prettyoutput

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

Features

• 🚀 Fast – 2x-3x faster than node:util.inspect.
• 🎨 Customizable – Adjust indentation, colors, depth, and more.
• 🌍 Cross-platform – Works with Node.js, Deno, Bun, and as a CLI.
• 🎭 Colorful output – Highlights keys, strings, and numbers.
• 📦 ESM & CJS – Supports both module systems.
• 🔒 TypeScript – Fully typed for safety and modern dev.
• ✅ Simple & tested – Easy to use, with solid test coverage.
• 🛠 Minimal – No dependencies, except commander.js for CLI.

Installation

1npm  add @tduyng/prettyoutput
2yarn add @tduyng/prettyoutput
3pnpm add @tduyng/prettyoutput

Usage

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

1import { prettyOutput } from '@tduyng/prettyoutput'
2
3const data = {
4    username: 'tduyng',
5    url: 'https://github.com/tduyng',
6    projects: ['@tduyng/prettyoutput', '@tduyng/logger'],
7}
8
9console.log(prettyOutput(data))

Sample output:

1username: tduyng
2url: https://github.com/tduyng
3projects:
4  - @tduyng/prettyoutput
5  - @tduyng/logger

Other example:

API

prettyOutput(data, options, indent)

Parameters

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

Options

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

Colors Options

1- {string} [keys] : Objects keys color. Default: green
2- {string} [dash] : Array prefixing dash ("- "). Default: green
3- {string} [number] : Numbers color. Default: blue
4- {string} [string] : Strings color. Default: no color
5- {string} [true] : Boolean value 'true' color. Default: green
6- {string} [false] : Boolean value 'false' color. Default: red
7- {string} [null] : 'Null' color. Default: grey
8- {string} [undefined] : 'Undefined' color. Default: grey

Example using options :

1import { prettyOutput } from '@tduyng/prettyoutput'
2
3const data = {
4    username: 'tduyng',
5    url: 'https://github.com/tduyng',
6    projects: ['@tduyng/prettyoutput', '@tduyng/logger'],
7}
8
9const options = {
10    noColor: true,
11    maxDepth: 5,
12    colors: {
13        keys: 'blue',
14        null: 'red',
15    },
16}
17
18console.log(prettyOutput(data, options, 2))

CLI Usage

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

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:

1# Pretty print a JSON file
2pretty package.json             # for ESM
3prettyoutput package.json       # for ESM
4pretty-cjs package.json         # for CJS
5prettyoutput-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.

1# Format with custom indentation, depth, and no color
2prettyoutput --indent=4 --depth=5 --noColor package.json

or

1# Indent 4, max depth 5, disable colors
2cat package.json | prettyoutput --indent=4 --depth=5 --noColor

1# Pretty print a JSON file
2prettyoutput package.json       # for ESM
3pretty package.json             # for ESM
4prettyoutput-cjs package.json   # for CJS
5pretty-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.

1# Format with custom indentation, depth, and no color
2prettyoutput --indent=4 --depth=5 --noColor package.json

or

1# Indent 4, max depth 5, disable colors
2cat 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 1.x-3.x times faster.

Run Benchmarks

1pnpm run benchmark

Benchmark Results

Tested on Node.js 22.8.0

1LEVELS | KEYS | LOOPS | WEIGHTS
23      | 20   | 100   | serializable: 0.9    array: 0.3    object: 0.5    multilineString: 0.3    error: 0.2
3
4NAME             | MIN                 | MAX                 | MEAN                | TOTAL
5prettyoutput    | 1 ms 417 µs 200 ns  | 35 ms 930 µs 467 ns | 2 ms 5 µs 439 ns    | 200 ms 543 µs 970 ns
6prettyjson       | 4 ms 56 µs 696 ns   | 9 ms 317 µs 632 ns  | 4 ms 473 µs 214 ns  | 447 ms 321 µs 437 ns
7util.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
8@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
9--------------------------------------------------------------------------------------------------------------
10
11
12LEVELS | KEYS | LOOPS | WEIGHTS
134      | 20   | 100   | serializable: 0.9    array: 0.3    object: 0.5    multilineString: 0.3    error: 0.2
14
15NAME             | MIN                 | MAX                  | MEAN                | TOTAL
16prettyoutput    | 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
17prettyjson       | 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
18util.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
19@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
20--------------------------------------------------------------------------------------------------------------
21
22
23LEVELS | KEYS | LOOPS | WEIGHTS
244      | 40   | 200   | serializable: 0.9    array: 0.3    object: 0.5    multilineString: 0.3    error: 0.2
25
26NAME             | MIN                     | MAX                      | MEAN                     | TOTAL
27prettyoutput    | 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
28prettyjson       | 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
29util.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
30@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
31--------------------------------------------------------------------------------------------------------------
32
33
34LEVELS | KEYS | LOOPS | WEIGHTS
355      | 20   | 100   | serializable: 0.9    array: 0.3    object: 0.5    multilineString: 0.3    error: 0.2
36
37NAME             | MIN                  | MAX                      | MEAN                    | TOTAL
38prettyoutput    | 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
39prettyjson       | 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
40util.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
41@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
42--------------------------------------------------------------------------------------------------------------

For detailed benchmark results, refer to the benchmark documentation.

Testing

Clone the repository and install development dependencies:

1pnpm install

Run tests:

1pnpm run test
2# 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.