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// Let's say that your age :)
let age = 30;

// This should never happen in real life...
// You just can't divide number with string!
age = age / '2';

// Ohh... Am I seeing 15 as a result?
// WOW JS... Is it a miracle? Or just implicit coercion?
console.log(age); // 15

bartcis

// declare your variable - default type - number
// Type is assigned to a value eg. 10 is a number (not variable level)
let level = 10;

// I change numeric value of level's value
level = 15;

// I change value type to string - explicit coercion
level = String(level);

bartcis

function sumPrimesInt(number) {
  function findPrimes(value) {
    // 1. Loop through defined range, (0 and 1 are not primes so skip them)
    for (let i = 2; i <= value; i++) {
      // 2. Those numers are not primes
      if (value % i === 0 && value != i) {
        return false;
      }
    }
    // 3. If the loop completed a number is prime

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function sumPrimesBasic(number) {
  // 1. Create final sum and call function for finding primes
  const findPrimes = (maximum) => {
    // 2. Inside function that finds prime declare initial variables
    let filter = [],
      primes = [];

    // 3. Loop through number smaller than the argument
    for (let i = 2; i <= maximum; i++) {
      // 4. This array contains multiplications. If it's there a number can't be prime

bartcis

// 1. Build an object with particular entities
const htmlEntities = {
  '&': '&',
  '<': '&lt;',
  '>': '&gt;',
  '"': '&quot;',
  "'": '&apos;'
};

function convertHTMLAdv(string, entities) {

bartcis

function convertHTMLInt(string) {
  // 1. Use build in replace method and RegExp to change characters
  return string
    .replace(/&/g, '&')
    .replace(/</g, '&lt;')
    .replace(/>/g, '&gt;')
    .replace(/"/g, '&quot;')
    .replace(/'/g, '&apos;');
}

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// Convert HTML characters

function convertHTMLBasic(string) {
  // 1. Convert a string into array and check each element
  let array = string.split('').map((a) => {
    // 2. If an element match to defined HTML entity
    // replace it with text eqivalent
    switch (a) {
      case '<':
        a = '&lt;';

bartcis

// Conver Arabic to Roman Numbers

function romanConventerBasic(number) {
  // 1. Create array with roman numbers and arabic equivalents
  const decimalValue = [1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1];
  const romanValue = ['M','CM','D','CD','C','XC','L','XL','X','IX','V','IV','I'];

  // 2. New variable that will be romanized number
  let romanized = '';

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// All odd Fibbonaci's
function sumOddFibsAdv(number) {
  // 1. Create array with the two first values from the sequence
  let fibs = [0, 1];

  // 2. Create the number sequence till defined parameter
  for (let fib = 1; fib <= number; ) {
    fibs.push(fib);
    fib = fibs[fibs.length - 1] + fibs[fibs.length - 2];
  }

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// All odd Fibbonaci's
function sumOddFibsBasic(number) {
  // 1. Create variables storing two latest values from the Fibbonaci numbers
  // and value of a final sum off only odd numbers
  let previousNum = 0;
  let currentNum = 1;
  let result = 0;

  // 2. While loop iterates as long as current value is smaller that function parameter
  while (currentNum <= number) {