pretty-var-export

pretty-var-export

Export any value to valid and equivalent JavaScript code. Uses syntax coloring for debugging from the cli.

npm install pretty-var-export

Usage

import pretty from 'pretty-var-export';

// return string suitable for logging
console.log(pretty(myValue));

// OR prettify and log
pretty.log(myValue1, myValue2);

Note that coloring can be disabled with pretty.colors.disable().

Example output

Customization

• Add handler
• Remove handler
• Custom indent
• Custom colors
• Custom display options
• Custom labels

Add handler

Add custom handlers for formatting.

For example, to show NaN as a different color than numbers:

import pretty from 'pretty-var-export';

// each handler must have a test and format method
pretty.handlers.add('nan', {
	test: isNaN,
	format: () => pretty.colors.palette.cyan('NaN'),
});

// if you want to reset to default list
pretty.handlers.reset();

Remove handler

You can remove handlers by name.

import pretty from 'pretty-var-export';

// see below for list of names
pretty.handlers.remove('nan');

// or you can reset all handlers
pretty.handlers.reset();

Default handler names:

• arguments
• Array
• BigInt
• Boolean
• Date
• Error
• Entries
• Function
• Map
• null
• Number
• Object
• Promise
• RegExp
• Set
• String
• Symbol
• TypedArray
• undefined
• URL
• URLSearchParams
• WeakMap
• WeakSet

Custom indent

By default, indentation is 2 spaces.

import pretty from 'pretty-var-export';

pretty.options.indent = 4; // 4 spaces
pretty.options.indent = '    '; // 4 spaces
pretty.options.indent = '\t'; // tab

Custom colors

Colors come from the ansi-colors npm module.

Formats include the following:

• boolean for true and false (default yellow)
• comment for comments (default gray)
• constructor for instantiation (default blue)
• escape for string escapes (default yellowBright)
• null for null (default yellow)
• number for numbers, NaN, Infinity (default red)
• property for object property names (default cyan)
• regexp for bodies of regular expressions (default blue)
• string for strings (default green)
• symbol for quotes, braces, parens, commas, colons (default white)
• undefined for undefined (default yellow)

import pretty from 'pretty-var-export';

// existing color functions from the ansi-colors npm package
pretty.colors.symbol = pretty.colors.palette.blueBright;

// use any other function
pretty.colors.string = chalk.green;

// disable all coloring
pretty.colors.disable();

// reset to default colors and re-enable coloring
pretty.colors.reset();

Custom display options

There are a few options that can change display. Below are defaults.

import pretty from 'pretty-var-export';

// if true, show function bodies
pretty.options.showFunctionBody = false;

// the max length for strings
pretty.options.maxStringLength = 1024 * 4;

// max number of items to list
pretty.options.maxListItems = 100;

// output multi-line strings with backticks
pretty.options.preferBackticks = true;

// quote style for default strings (single, double or backtick)
pretty.options.quoteStyle = 'double';

// reset to defaults
pretty.options.reset();

Custom labels

Labels can be changed or translated.

import pretty from 'pretty-var-export';

// defaults
pretty.labels.circularReference = 'Circular Reference';
pretty.labels.codeOmitted = 'Code Omitted';
pretty.labels.itemsUnknown = 'Items Unknown';

// reset to defaults
pretty.labels.reset();

Changelog

See CHANGELOG.md

Contributing

Please open a ticket or PR on GitHub.

License

MIT License