Helper Functions in Javascript

helperFunctions.js

/**
 * FUNCTION shuffles an array passed and return a shuffled array with 
 * new positions for all array elements.
 * More in this shuffle techniques can be found here on link below
 * https://bost.ocks.org/mike/shuffle/
 * 
 * @param {Array} arr - array to be shuffled
 * @returns {Array} array - new shuffled array.
 */

function shuffle (array) {
  var currentIndex = array.length,
    randomIndex;

  // While there remain elements to shuffle...
  while (0 !== currentIndex) {
    // Pick a remaining element...
    randomIndex = Math.floor(Math.random() * currentIndex);
    currentIndex--;

    // And swap it with the current element.
    [ array[currentIndex], array[randomIndex] ] = [ array[randomIndex], array[currentIndex] ];
  }

  return array;
}

/**
 * const picks random number of specified elements in an array and will return
 * random (n) numbers from the array length
 * 
 * @param {Array} arr - array of elements to pick from
 * @param {Number} [count=7] - count of elements to be returned
 * 
 * @returns {Array} - array containing number of elements with length of count
 */

function pickRandomArrayElements (arr, count = 7) {
  let _arr = [ ...arr ];
  return [ ...Array(count) ].map(() => _arr.splice(Math.floor(Math.random() * _arr.length), 1)[0]);
}

/**
 * function validates email addresses.
 * 
 * @param {String} email 
 * @returns {Boolen}
 */
function ValidateEmail (email) {
  if (/^\w+([\.-]?\w+)*@\w+([\.-]?\w+)*(\.\w{2,3})+$/.test(email)) return true;
  return false;
}

/**
 * Function returns iso date strig with Time Offset of region.
 * @param {date} d 
 * @returns {date}
 */
function local1 (d = new Date()) {
  // const tzoffset = d.getTimezoneOffset() * 60000;//offset in milliseconds.
  // return (new Date(Date.now() - tzoffset)).toISOString().slice(0, -1);
  return new Date(Date.now() - d.getTimezoneOffset() * 60000).toISOString().slice(0, -1);
}

/**
 * Function formats number by thousands comma separator e.g '1020303' will return '1,020,303'
 * @param {String} x
 * @returns {String} 
 */
function numberFormattedWithCommas (x) {
  return x.toString().replace(/\B(?=(\d{3})+(?!\d))/g, ',');
}

/**
 * 
 * @param {String | Number} number 
 * @param {Number} fix 
 * @param {Boolean} caps 
 * @returns String
 */
export const currencyFormatter = (number, fix = 1, caps = false) => {
  const num = parseInt(number);
  // if (typeof num !== Number)
  //   return Alert.alert('Not a number', 'the value parse to be converted is not a number, try again');

  const SYM = caps ? [ '', 'K', 'M', 'B', 'T', 'P', 'E' ] : [ '', 'k', 'm', 'b', 't', 'p', 'e' ];

  // what tier? (determines SI symbol)
  var tier = (Math.log10(Math.abs(num)) / 3) | 0;

  // if zero, we don't need a suffix
  if (tier == 0) return number;

  // get suffix and determine scale
  var suffix = SYM[tier];
  var scale = Math.pow(10, tier * 3);

  // scale the number
  var scaled = number / scale;

  // format number and add suffix
  return scaled.toFixed(fix) + suffix;
};

export const isoStringWithoutOffset = () =>
  new Date(Date.now() - new Date().getTimezoneOffset() * 60000).toISOString().slice(0, -1);

// Splits array of n-size into size of 10 since its the limit for firestore in operator in the above function
export const getArraychunks = (array, size) => {
  var results = [];
  while (array.length) {
    results.push(array.splice(0, size));
  }
  // console.log('CHUNK', results);
  return results;
};

export const getDatesBetweenRange = function (startDate, endDate) {
  // Start Date format should be YYYY-MM-DD
  // End Date format should be YYYY-MM-DD

  var dates = [];

  // Get the day to start from.
  var currDate = moment(startDate).startOf('day');

  // Add one day to the end date to return the end date as well
  var lastDate = moment(endDate).startOf('day');

  // Get the difference in days
  // < 0 to exclude the end date, but use < 1 to include last day.
  while (currDate.add(1, 'days').diff(lastDate) < 1) {
    // console.log(moment(currDate).format('DD-MM-YYYY'));
    dates.push(moment(currDate).format('DD-MM-YYYY'));
  }

  return dates;
};

/** Function groups an array of objects by a passed key
 * 
 * @param {x} x Array
 * @param {f} f key
 * @returns Object
 */
export const groupBy = (x, f) => x.reduce((a, b) => ((a[f(b)] || []).push(b), a), {});