pretty-var-export/README.md

Export any value to valid and equivalent JavaScript code

# pretty-var-export

[![Build Status](https://travis-ci.com/kensnyder/pretty-var-export.svg?branch=master&v=2.0.2)](https://travis-ci.org/kensnyder/pretty-var-export)
[![Code Coverage](https://codecov.io/gh/kensnyder/pretty-var-export/branch/master/graph/badge.svg?v=2.0.2)](https://codecov.io/gh/kensnyder/pretty-var-export)
[![MIT License](https://img.shields.io/github/license/kensnyder/pretty-var-export.svg?v=2.0.2)](https://opensource.org/licenses/MIT)

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

```bash
npm install pretty-var-export
```

## Usage

```ts
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

![Example](./demo/example.png?raw=true&v=2.0.2)

## Customization

- [Add handler](#add-handler)
- [Remove handler](#remove-handler)
- [Custom indent](#custom-indent)
- [Custom colors](#custom-colors)
- [Custom display options](#custom-display-options)
- [Custom labels](#custom-labels)

### Add handler

Add custom handlers for formatting.

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

```ts
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.

```ts
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.

```ts
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](https://npmjs.com/package/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)

```ts
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.

```ts
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.

```ts
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](./CHANGELOG.md)

## Contributing

Please open a ticket or PR on GitHub.

## License

[MIT License](./LICENSE)