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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.

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'

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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>

© 2014-24 Lloyd Brookes <[email protected]>.

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