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byte-size

An isomorphic, load-anywhere function to convert a bytes value (e.g. 3456) to a human-readable string ('3.5 kB'). Choose between metric or IEC units (summarised below) or specify your own custom units.

Value | Metric | Metric (octet) | ----- | ------------- | -------------- | 1000 | kB kilobyte | ko kilooctet | 1000^2 | MB megabyte | Mo megaoctet | 1000^3 | GB gigabyte | Go gigaoctet | 1000^4 | TB terabyte | To teraoctet | 1000^5 | PB petabyte | Po petaoctet | 1000^6 | EB exabyte | Eo exaoctet | 1000^7 | ZB zettabyte | Zo zettaoctet | 1000^8 | YB yottabyte | Yo yottaoctet |

Value | IEC | IEC (octet) | ------ | ------------ | ------------- | 1024 | KiB kibibyte | Kio kibioctet | 1024^2 | MiB mebibyte | Mio mebioctet | 1024^3 | GiB gibibyte | Gio gibioctet | 1024^4 | TiB tebibyte | Tio tebioctet | 1024^5 | PiB pebibyte | Pio pebioctet | 1024^6 | EiB exbibyte | Eio exbioctet | 1024^7 | ZiB zebibyte | Zio zebioctet | 1024^8 | YiB yobibyte | Yio yobioctet |

Synopsis

By default, byteSize converts the input number to a human readable string with metric units and a precision of 1.

> const byteSize = require('byte-size')

> byteSize(1580)
{ value: '1.6', unit: 'kB', long: 'kilobytes' }

The object returned by byteSize defines a toString method therefore can be used directly in string context.

> `Filesize: ${byteSize(12400)}`
'Filesize: 12.4 kB'

Override the default toString behaviour by setting options.toStringFn.

> function toStringFn () {
  return `**${this.value}${this.unit}**`
}

> `Filesize: ${byteSize(12400, { toStringFn })}`
'Filesize: **12.4kB**'

Beside the default of metric, there are three other built-in units available: metric_octet, iec and iec_octet.

> byteSize(1580, { units: 'iec' })
{ value: '1.5', unit: 'KiB', long: 'kibibytes' }

> byteSize(1580, { units: 'iec_octet' })
{ value: '1.5', unit: 'Kio', long: 'kibioctets' }

> byteSize(1580, { units: 'metric_octet' })
{ value: '1.6', unit: 'ko', long: 'kilooctets' }

You can adjust the precision.

> byteSize(1580, { units: 'iec', precision: 3 })
{ value: '1.543', unit: 'KiB', long: 'kibibytes' }

> byteSize(1580, { units: 'iec', precision: 0 })
{ value: '2', unit: 'KiB', long: 'kibibytes' }

Define custom units by passing an object containing one or more additional conversion tables to options.customUnits. In options.units, specify the name of a property from the customUnits object.

> const customUnits = {
  simple: [
    { from: 0   , to: 1e3 , unit: ''  },
    { from: 1e3 , to: 1e6 , unit: 'K', long: 'thousand' },
    { from: 1e6 , to: 1e9 , unit: 'Mn', long: 'million' },
    { from: 1e9 , to: 1e12, unit: 'Bn', long: 'billion' }
  ]
}

> const { value, unit } = byteSize(10000, { customUnits, units: 'simple' })

> `${value}${unit}`
'10.0K'

Override the built-in defaults for the duration of the process by passing an options object to byteSize.defaultOptions(). This results in cleaner code in cases where byteSize is used often with the same options.

> byteSize.defaultOptions({
  units: 'simple',
  precision: 2,
  customUnits: {
    simple: [
      { from: 0, to: 1e3, unit: '' },
      { from: 1e3, to: 1e6, unit: 'k' },
      { from: 1e6, to: 1e9, unit: 'm' },
      { from: 1e9, to: 1e12, unit: 'bn' },
    ]
  },
  toStringFn: function () {
    return this.value + this.unit
  }
})

> [2400, 16400, 3991200].map(byteSize).join(', ')
'2.40k, 16.40k, 3.99m'

byte-size

• byte-size
  • byteSize(bytes, [options]) ⇒ object ⏏
    • .defaultOptions(options)

byteSize(bytes, [options]) ⇒ object ⏏

Returns an object with the spec { value: string, unit: string, long: string }. The returned object defines a toString method meaning it can be used in any string context.

Kind: Exported function

| Param | Type | Description | | --- | --- | --- | | bytes | number | The bytes value to convert. | | [options] | object | Optional config. | | [options.precision] | number | Number of decimal places. Defaults to 1. | | [options.units] | string | Specify 'metric', 'iec', 'metric_octet', 'iec_octet' or the name of a property from the custom units table in options.customUnits. Defaults to metric. | | [options.customUnits] | object | An object containing one or more custom unit lookup tables. | | [options.toStringFn] | function | A toString function to override the default. | | [options.locale] | string | Array.<string> | Node >=13 or modern browser only - on earlier platforms this option is ignored. The locale to use for number formatting (e.g. 'de-DE'). Defaults to your system locale. Passed directed into Intl.NumberFormat(). |

byteSize.defaultOptions(options)

Set the default byteSize options for the duration of the process.

Kind: static method of byteSize

| Param | Type | Description | | --- | --- | --- | | options | object | A byteSize options object. |

Load anywhere

This library is compatible with Node.js, the Web and any style of module loader. It can be loaded anywhere, natively without transpilation.

Node.js (CommonJS):

const byteSize = require('byte-size')

Node.js (ECMAScript Module):

import byteSize from 'byte-size'

Within a modern browser ECMAScript Module:

import byteSize from './node_modules/byte-size/index.js'

Browser global (adds window.byteSize):

<script src="./node_modules/byte-size/dist/index.js"></script>

© 2014-25 Lloyd Brookes <[email protected]>.

Tested by test-runner. Documented by jsdoc-to-markdown.