0xD34F

$('.photo-link').val(function() {
  return $(this).parent().find('.ulightbox').attr('href');
});

document.querySelectorAll('.photo-link').forEach(n => {
  n.value = n.parentNode.querySelector('.ulightbox').getAttribute('href');
});

- Words.prototype[Symbol.iterator] = () => {
+ Words.prototype[Symbol.iterator] = function() {

- next() {
+ next: () => {

$('#btn').click(function() {
  i = (i + 1) % arrLatLng.length;
  map.setCenter(arrLatLng[i]);
});

const containerSelector = '.info';
const buttonSelector = `${containerSelector} button`;
const props = [ 'quantity', 'square', 'floor' ];
const { elements } = document.querySelector('form');

document.addEventListener('click', ({ target: t }) => {
  if (t.matches(buttonSelector)) {
    props.forEach(function(n) {
      elements[n].value = this.querySelector(`.${n}`).textContent;
    }, t.closest(containerSelector));
  }
});

const result = arr.reduce((acc, n, i) => (
  acc.push(...(i & 1 ? n : [...n].reverse())),
  acc
), []);

for (let i = 0; i < arr.length; ++i) {
  const a = i & 1 ? arr[i] : [...arr[i]].reverse();
  for (let j = 0; j < a.length; ++j) {
    result.push(a[j]);
  }
}

function showTooltip(link) {
  const div = link.parentNode.querySelector('div');

  if (div.style.display === 'none') {
    div.style.display = 'block';
    link.style.display = 'none';
  } else {
    div.style.display = 'none';
  }
}

document.querySelectorAll('.contacts-number a').forEach(n => {
  n.addEventListener('click', onClick);
});

function onClick() {
  const div = this.closest('.contacts-number').querySelector('div');

  if (div.style.display === 'none') {
    div.style.display = 'block';
    this.style.display = 'none';
  } else {
    div.style.display = 'none';
  }
}

пока кроме ошибок ничего не получил

document.querySelectorAll('.test').forEach(n => {
  n.textContent = n.textContent.replace(/\bAenean\b/g, 'Aenean1');
});

// или

for (const n of document.getElementsByClassName('test')) {
  n.innerText = n.innerText.replace(/\bAenean\b/g, '$&1');
}

<div>
  <button data-step="-1">-</button>
  <button data-step="+1">+</button>
</div>
<textarea cols="30" rows="10"></textarea>

const history = JSON.parse(localStorage.getItem('history')) || [];
let index = history.length - 1;

const $text = $('textarea').change(function() {
  index = history.push($text.val()) - 1;
  localStorage.setItem('history', JSON.stringify(history));
});

$('[data-step]').click(function() {
  goTo(index + +this.dataset.step);
});

goTo(index);

function goTo(newIndex) {
  if (0 <= newIndex && newIndex <= history.length - 1) {
    index = newIndex;
    $text.val(history[index]);
  }
}

$('.block').on('mouseout', function() {
  this.style.transform = '';
});

arr.map(id => people.find(n => n.id === id))

// или

arr.map(function(n) {
  return this[n];
}, people.reduce((acc, n) => (acc[n.id] = n, acc), {}))

people.filter(n => arr.includes(n.id))

// или

people.filter(((ids, n) => ids.has(n.id)).bind(null, new Set(arr)))

<ul>
  <li><span>aaa</span></li>
  <li>
    <span>bbb</span>
    <ul>
      <li><span>bbb.1</span></li>
      <li>
        <span>bbb.2</span>
        <ul>
          <li><span>bbb.2.1</span></li>
          <li><span>bbb.2.2</span></li>
        </ul>
      </li>
      <li>
        <span>bbb.3</span>
        <ul>
          <li>
            <span>bbb.3.1</span>
            <ul>
              <li><span>bbb.3.1.1</span></li>
            </ul>
          </li>
        </ul>
      </li>
    </ul>
  </li>
</ul>

document.querySelectorAll('li').forEach(n => {
  const count = ((n.querySelector('ul') || {}).children || []).length;
  n.querySelector('span').textContent += ` (${count})`;
});

document.querySelectorAll('li').forEach(n => {
  const count = n.querySelectorAll('li').length;
  n.querySelector('span').textContent += ` (${count})`;
});

(((lead._embedded.items[0].custom_fields.find(cf => cf.id == PRODUCT_FIELD_ID) || {}).values || {})[0] || {}).value || null

lead._embedded.items[0].custom_fields.find(cf => cf.id == PRODUCT_FIELD_ID)?.values[0].value ?? null

class TestClass {
  constructor() {
    const self = el => self.data.push(el);
    Object.setPrototypeOf(self, TestClass.prototype);

    self.data = [];

    return self;
  }

  toString() {
    return this.data.join('');
  }
}

document.querySelectorAll(`.${className}`).forEach((n, i) => {
  n.innerText = arr[i];
});

// или

const elems = document.getElementsByClassName(className);
for (let i = 0; i < elems.length; i++) {
  elems[i].textContent = arr[i];
}

// или

$('.' + className).text(i => arr[i]);

$(window).scroll(function onScroll() {
  if ($(this).scrollTop() > 777) {
    $('.div_clone').clone().appendTo('.container2');
    $(this).off('scroll', onScroll);
  }
});

const isAllUnique = (...args) => new Set(args).size === args.length;

console.log(isAllUnique(69, 187, 666)); // true
console.log(isAllUnique(2, 2, 3, 4)); // false
console.log(isAllUnique(...'ABCDA')) // false

const elems = [...document.querySelectorAll('.class1')];
const index = elems.findIndex(n => n.classList.contains('class2'));

const elems = document.querySelectorAll('.class1');
let index = elems.length;
while (--index >= 0 && !elems[index].matches('.class2')) ;

const index = Array.prototype.indexOf.call(
  document.querySelectorAll('.class1'),
  document.querySelector('.class2')
);

<div class="country">
  <input class="country-code">
  <img class="country-flag">
</div>

function updateFlag(el) {
  const country = countries.find(n => !el.value.indexOf(n.code));
  el.closest('.country').querySelector('.country-flag').src = country ? country.flag : '';
}

document.addEventListener('input', function(e) {
  if (e.target.classList.contains('country-code')) {
    updateFlag(e.target);
  }
});

document.querySelectorAll('.country-code').forEach(updateFlag);

const countries = [
  { code: ..., flag: ... },
  { code: ..., flag: ... },
  ...
];

const country = countries.find(n => !inputCode.value.indexOf(n.code));
inputFlag.src = country ? country.flag : '';