file-commons/src/formatFileSize.ts

import numeral from 'numeral'

type FormatFileSize = (n: number, raw?: boolean) => string

const formatFileSize: FormatFileSize = (n, raw = false) => {
  if ((typeof n as unknown) !== 'number') {
    throw TypeError('Argument should be a number.')
  }

  if (isNaN(n)) {
    throw RangeError('Cannot format NaN.')
  }

  if (n < 0) {
    throw RangeError('Cannot format negative values.')
  }

  if (n === Number.POSITIVE_INFINITY) {
    throw RangeError('Cannot format infinity.')
  }

  if (raw) {
    const absValue = Math.abs(n)
    const base = numeral(absValue < 1000 ? absValue : 999).format('0 b')
    const suffix = base.slice(base.indexOf(' ') + ' '.length)
    return `${numeral(absValue).format('0,0')} ${suffix}`
  }

  return numeral(Math.abs(n)).format(Math.abs(n) < 1000 ? '0 b' : '0.00 b')
}

export default formatFileSize