0xD34F

const urls = [
  'http://sitename.net/somedirectory/14545/',
  'http://sitename.net/somedirectory/14545/count-1145',
  'http://sitename.net/somedirectory/14545/specific-345',
  'http://sitename.net/somedirectory/14545/count-1145/specific-345',
];

const getParams = (url, params) =>
  params instanceof Array && params.length
    ? (url.match(RegExp(`(${params.join('|')})-\\d+`, 'g')) || [])
        .map(n => n.split('-'))
        .reduce((acc, n) => (acc[n[0]] = n[1], acc), {})
    : {};

const params = urls.map(n => getParams(n, [ 'count', 'specific' ]));

const getParams = url =>
  Object.fromEntries((url
    .match(/[a-z]+-\d+/g) || [])
    .map(n => n.split('-'))
  );

.dropdown-checkbox ul.opened {
  display: block;
}

<label @click="opened = !opened">click me</label>
<ul :class="{ opened }">
  ...

data: () => ({
  opened: false,
}),

const [ first, second ] = [...arr]
  .sort((a, b) => b.id - a.id)
  .slice(0, 2)
  .map(n => n.name);

const [ { name: first }, { name: second } ] = arr.reduce((acc, n) => {
  if (!(acc[0].id >= n.id)) {
    acc[1] = acc[0];
    acc[0] = n;
  } else if (!(acc[1].id >= n.id)) {
    acc[1] = n;
  }
  return acc;
}, [ {}, {} ]);

cildren

const copyTree = (tree, f) =>
  tree.map(n => {
    n = f instanceof Function ? f(n) : { ...n };
    if (n.children instanceof Array) {
      n.children = copyTree(n.children, f);
    }
    return n;
  });


const dataCopy = copyTree(data, ({ name: key, ...x }) => ({ key, ...x }));

const sequence = (length, pattern) =>
  pattern instanceof Function
    ? Array.from({ length }, pattern)
    : Array(length).fill(pattern);

const select = document.querySelector('#country');
const value = 'europe';

const options = select.querySelectorAll(`option[value*="${value}"]`);

const options = Array.prototype.filter.call(
  select.options,
  n => n.value.includes(value)
);

const options = [];
for (const n of select.children) {
  if (n.value.indexOf(value) !== -1) {
    options.push(n);
  }
}

document.querySelector('.allstatus-btn').addEventListener('click', () => {
  const items = Object.fromEntries(Array.from(
    document.querySelectorAll('.number-all'),
    n => [ n.innerText, n ]
  ));

  fetch('https://api.novaposhta.ua/v2.0/json/', {
    method: 'POST',
    body: JSON.stringify({
      modelName: 'TrackingDocument',
      calledMethod: 'getStatusDocuments',
      methodProperties: {
        Documents: Object.keys(items).map(n => ({
          DocumentNumber: n,
          Phone: '',
        })),
      },
      apiKey: '',
    }),
  })
    .then(r => r.json())
    .then(r => r.data.forEach(n => items[n.Number].innerHTML += n.Status));
});

this.setState(({ events }) => ({
  events: events.map(n => n.id === id ? { ...n, title: newTitle } : n),
}));

function createTree(data) {
  const obl = {};
  const org = {};
  const podr = {};

  data.forEach(n => {
    obl[n.obl.id] = { ...n.obl, children: [] };
    org[n.org.id] = { ...n.org, children: [] };
    podr[n.podr.id] = { ...n.podr, children: [] };
  });

  data.forEach(n => podr[n.podr.id].children.push({ ...n.dolzh }));
  Object.values(org).forEach(n => obl[n.parent_obl].children.push(n));
  Object.values(podr).forEach(n => org[n.parent_org].children.push(n));

  return Object.values(obl);
}


const tree = createTree(arr);

computed: {
  msg() {
    return this.$t('welcomeMsg');
  },
},

Array.from([...str].reduce((acc, n) => acc.set(n, -~acc.get(n)), new Map), n => n[1] + n[0])

str.split('').sort().join('').match(/(.)\1*/g).map(n => n.length + n[0])

Array.from(new Set(str), n => str.replace(RegExp(`[^${n}]`, 'g'), '').length + n)

const walk = (el, level = 0) =>
  [...el.children].reduce((p, c) => {
    c = walk(c, level + 1);
    return p.level > c.level ? p : c;
  }, { el, level });

const getLastDeepestElement = root => walk(root).el;

const getDeepestLastElement = el =>
  el.lastElementChild
    ? getDeepestLastElement(el.lastElementChild)
    : el;

// или, без рекурсии
const getDeepestLastElement = el => Array
  .from(el.querySelectorAll('*'))
  .pop() || el;

firebase.auth().onAuthStateChanged(user => {
  if (user) {
    store.dispatch('loggedUser', user);
  }

  new Vue(...);
});

.on('click', function(e) {
  e.stopPropagation();

function isComposite($num) {
  // нет, за вас я этого делать не буду, давайте как-нибудь сами...
  // в конце концов, можно и нагуглить - это дело трёх секунд
}

const valuesShow = [ 2000, ещё какое-то значение, и ещё, и ещё, ... ];

$('#sample_form_deliv').change(function({ target: { value } }) {
  $('#sample_form_pay .input-label:eq(2)').toggle(valuesShow.includes(+value));
});