convertSize.js

const units = ['bytes', 'kb', 'mb', 'gb', 'tb', 'pb', 'eb', 'zb', 'yb'];

export const getSizeFromBytes = x => {
  let l = 0,
    n = parseInt(x, 10) || 0;
  while (n >= 1024 && ++l) n = n / 1024;

  // include a decimal point and a tenths-place digit if presenting
  // less than ten of KB or greater units
  return n.toFixed(n < 10 && l > 0 ? 1 : 0) + ' ' + units[l];
};