pretty-format2

2.0.4 verified Sat Apr 25 auth: no javascript

pretty-format2 is a JavaScript library for stringifying any value into a human-readable format, designed to be faster and more feature-rich than alternatives like JSON.stringify, pretty-format, and util.inspect. Version 2.0.4 is a work-in-progress with no stable release yet; the package is experimental and subject to breaking changes. Key differentiators include support for plugins, custom indentation, color themes via ANSI escape codes, and a streaming API. It aims to be more performant than pretty-format and more customizable than util.inspect for both Node.js and browser environments.

Common errors

error TypeError: prettyFormat is not a function ↓

cause Using CommonJS require on an ESM-only package.

fix

Switch to ESM import: import { prettyFormat } from 'pretty-format2'

error SyntaxError: Unexpected token 'export' ↓

cause Using older Node.js version (<12) that doesn't support ESM syntax.

fix

Upgrade Node.js to version 12 or later, or use a transpiler like Babel.

error Module not found: Can't resolve 'ansi-styles' ↓

cause Optional dependency ansi-styles not installed but tried to use color theme.

fix

Install ansi-styles manually: npm install ansi-styles

error prettyFormat(...).highlight is not a function ↓

cause Passing options incorrectly: highlight should be a boolean, not invoked as a method.

fix

Use: prettyFormat(obj, { highlight: true })

Warnings

gotcha The package is marked as WIP and experimental; no stable release yet. Breaking changes may occur between minor versions. ↓

fix Pin to exact version and monitor releases for changes.

breaking Version 2.0.0 changed from a default export to named exports. CommonJS require broke. ↓

fix Use ESM import with named syntax: import { prettyFormat } from 'pretty-format2'.

deprecated The option 'colors' was renamed to 'theme' in version 2.0.0. The old name still works but will be removed in a future release. ↓

fix Replace `colors` with `theme` in the options object.

gotcha Highlight option only works in Node.js terminals that support ANSI escape codes. Browser output may show raw codes. ↓

fix Pre-check environment or provide a polyfill for ANSI sequences.

gotcha React element detection requires the optional dependency 'react-is'. If not installed, React elements will print as plain objects. ↓

fix Install react-is as a dependency: npm install react-is

Install

npm install pretty-format2

yarn add pretty-format2

pnpm add pretty-format2

Imports

prettyFormat

wrong

const prettyFormat = require('pretty-format2')

correct

import { prettyFormat } from 'pretty-format2'

The package is ESM-only; CommonJS require is not supported.

plugins
wrong
```
import plugins from 'pretty-format2/plugins'
```
correct
```
import { plugins } from 'pretty-format2'
```
Plugins are exported as a named export from the main entry, not a separate path.

PrettyFormatOptions

wrong

import { PrettyFormatOptions } from 'pretty-format2'

correct

import type { PrettyFormatOptions } from 'pretty-format2'

Use type import for TypeScript types to avoid runtime bundling issues.

Quickstart

Demonstrates basic usage of prettyFormat with options for indentation, function name printing, color theme, and highlighting.

import { prettyFormat } from 'pretty-format2';

const obj = {
  name: 'example',
  nested: { a: 1, b: 2 },
  date: new Date('2023-01-01'),
  regex: /test/gi,
  fn: function() { return true; },
  [Symbol('id')]: 42,
};

const formatted = prettyFormat(obj, {
  indent: 2,
  printFunctionName: true,
  highlight: true,
  theme: {
    key: 'yellow',
    string: 'green',
    number: 'blue',
    boolean: 'magenta',
    null: 'red',
    undefined: 'grey',
  },
});

console.log(formatted);