This is a helper.js

Helpers.js

/**
 * Get domain from string url
 * @param {*} url 
 * @returns string
 */
export const getDomain = url => {
  const urlParts = getApiUrl(url)
                    .split('/')
                    .slice(0, 3)
                    .join('/')
                    .split('.')  
  return urlParts
    .slice(0)
    .slice(-(urlParts.length === 4 ? 3 : 2))
    .join('.')
}

/**
 * Second to string
 * @param {number} seconds
 * @returns string
 */
export const secToStr = (seconds) => {
  const dateTime =  new Date(seconds * 1000).toISOString()
  return seconds > 3600 ? dateTime.slice(11, -5): dateTime.slice(14, -5)
}

/**
 * Random array with unique and length
 * @param {array} array => data you want to randomized
 * @param {number} n    => the length of the array what you want to randomized 
 * @param {float} unique =>  Unique number used for random array
 * @returns string
 */
export const randomArray = (array, n, unique) => {
  n = n == null ? 1 : n
  const length = array == null ? 0 : array.length
  if (!length || n < 1) {
    return []
  }
  n = n > length ? length : n
  let index = -1
  const lastIndex = length - 1
  const result = [...array]
  while (++index < n) {
    const rand = index + Math.floor(unique * (lastIndex - index + 1))
    const value = result[rand]
    result[rand] = result[index]
    result[index] = value
  }
  return _.slice(result, 0, n)
}


/**
 * Format file size
 * @param {number} bytes
 * @param {number} decimalPoint
 * @returns string
 */
export const formatFileSize = (bytes, decimalPoint) => {
  if (bytes === 0) return '0 Bytes';
  var k = 1000,
    dm = decimalPoint || 2,
    sizes = ['Bytes', 'KB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB'],
    i = Math.floor(Math.log(bytes) / Math.log(k));
  return parseFloat((bytes / Math.pow(k, i)).toFixed(dm)) + ' ' + sizes[i];
}

/**
* Countdown
* @param deadline new Date()
* @return object
*/
export const countdown = (deadline) => {

  const now = new Date().getTime();
  const t   = deadline - now;
  const dd  = Math.floor(t / (1000 * 60 * 60 * 24));
  const hh  = Math.floor((t % (1000 * 60 * 60 * 24)) / (1000 * 60 * 60));
  const mm  = Math.floor((t % (1000 * 60 * 60)) / (1000 * 60));
  const ss  = Math.floor((t % (1000 * 60)) / 1000);

  const getTrueNumber = (x) => {
    if (x<10) return '0'+x;
    else return x;
  }

  return {
    come   : t,
    day    : getTrueNumber(dd),
    hour   : getTrueNumber(hh),
    minute : getTrueNumber(mm),
    second : getTrueNumber(ss)
  }