formatBytes.ts, format bytes

formatBytes.ts

export const formatBytes = (bytes: number, options?: Intl.NumberFormatOptions) => {
  /**
   * Per {@link https://tc39.es/ecma402/#table-sanctioned-single-unit-identifiers},
   * these are the valid units for the "unit" style. Since each unit multiple is
   * considered a separate unit, we have to manually determine the appropriate unit
   * and corresponding value, otherwise we get formatting such as "1 BB" instead of
   * "1 GB".
   */
  const units = ["byte", "kilobyte", "megabyte", "gigabyte", "terabyte", "petabyte"];
  if (!bytes || bytes <= 0) return `0 ${units[0]}s`;

  // note, this is in base 10 and not base 2, so gigabyte = 1000 megabytes
  const exponent = Math.min(Math.floor(Math.log10(bytes) / 3), units.length - 1);
  const value = bytes / 1000 ** exponent;

  return new Intl.NumberFormat(undefined, {
    style: "unit",
    unit: units[exponent],
    unitDisplay: "long",
    ...options,
  }).format(value);
};

behavior acts a bit funny when bytes isn't an integer, but not sure should happen with decimals (... 1 byte and 4 bits...? 1.5 bytes? just round down to 1 byte? not sure)