yves

A customizable value inspector for Node.js, inspired by eyes.

Handles circular objects, pretty-prints object literals, and supports ANSI color output, HTML output, and debug integration.

Install

npm install yves

Requires Node.js >= 18.

Usage

import yves from 'yves'

yves.inspect(something)

With a label:

yves.inspect(something, 'my value')

With a custom inspector:

const inspect = yves.inspector({ styles: { all: 'magenta' } })

inspect(something)

To return the string instead of printing to stdout:

const inspect = yves.inspector({ stream: null })

console.log(inspect({ something: 42 }))

Options

Pass options to inspector() or as the third argument to inspect().

Styles

styles: {
    all:     'cyan',      // Overall style applied to everything
    label:   'underline', // Inspection labels, like 'array' in `array: [1, 2, 3]`
    other:   'inverted',  // Objects without a literal representation (functions)
    key:     'bold',      // Object keys, like 'a' in `{a: 1}`
    special: 'grey',      // null, undefined
    string:  'green',
    number:  'magenta',
    bool:    'blue',
    regexp:  'green',
}

Available styles: bold, underline, inverse, cyan, magenta, blue, yellow, green, red, grey.

Set styles: false to disable all styling. Set colors: false to disable ANSI codes.

Formatting

| Option | Default | Description | |--------|---------|-------------| | pretty | true | Indent object literals and arrays | | indent | 4 | Spaces per indentation level | | singleLineMax | 2 | Max keys before an object is printed multiline | | trailingComma | true | Add trailing commas in multiline output | | templateStrings | true | Use backtick syntax for strings containing newlines/tabs | | escape | true | Escape invisible characters in strings | | json | false | Use JSON-style output (double-quoted keys and strings) | | sortKeys | false | Sort object keys alphabetically | | sorted | false | Deep-sort the input object before inspecting |

Truncation

| Option | Default | Description | |--------|---------|-------------| | maxLength | -1 | Max output length in characters (-1 for unlimited) | | maxStringLength | - | Truncate strings beyond this length | | maxArrayLength | - | Show at most N array elements | | maxObjectKeys | - | Show at most N object keys |

Filtering

| Option | Default | Description | |--------|---------|-------------| | includes | null | Only show keys matching these strings/regexps | | excludes | null | Hide keys matching these strings/regexps | | obfuscates | null | Replace values of matching keys with <<obfuscated>> | | hideFunctions | false | Omit function-valued properties |

yves.inspect(obj, 'filtered', {
    includes: ['name', /^user/],
    obfuscates: ['password', /secret/],
})

Output

| Option | Default | Description | |--------|---------|-------------| | stream | process.stdout | Writable stream, or null to return the string | | colors | auto-detected | Enable ANSI color codes | | html | false | Output HTML <span> tags instead of ANSI codes | | decycle | true | Safely handle circular references |

HTML output

const inspect = yves.inspector({ stream: null, html: true, colors: true })

const html = inspect({ hello: 'world' })
// Returns a <pre> block with <span> color styling

Debug integration

yves integrates with the debug module. Use the %y formatter for compact output or %Y for sorted, function-free output:

import debug from 'debug'
const log = debug('app')

log('user data: %y', userData)

Console hijacking

Replace console.log / console.dir etc. with yves-powered output routed through debug:

yves.console('myapp')

console.log('hello')   // now outputs via debug('myapp:console:log')
console.dir({ a: 1 })  // pretty-printed via yves

yves.console_unset()   // restore original console

API

• yves.inspect(obj, label?, options?) -- inspect and print to stream
• yves.inspector(options?) -- returns a reusable inspect function
• yves.options(opts) -- update global defaults
• yves.stylize(str, style, options) -- apply a single ANSI/HTML style
• yves.typeOf(value) -- enhanced typeof (distinguishes array, regexp, date, buffer, null, bigint)
• yves.debugger(namespace) -- create a debug logger
• yves.console(namespace?) -- hijack console with debug-powered output
• yves.console_unset() -- restore original console methods

License

MIT