0xD34F

<v-data-table
  :headers="mainTableHeaders"
  :items="mainTableItems"
  item-key="mainTableItemKey"
  show-expand
>
  <template #expanded-item="{ headers, item }">
    <td :colspan="headers.length">
      <v-data-table
        :headers="nestedTableHeaders"
        :items="item.nestedTableItems"
      ></v-data-table>
    </td>
  </template>
</v-data-table>

при клике на строчку

methods: {
  onRowClick(item, row) {
    row.expand(!row.isExpanded);
  },
  ...

<v-data-table
  @click:row="onRowClick"
  ...

class DB {
  info = null;
  ...

const Episodes = observer(() => {
  useEffect(() => {
    ...
  }, [ DB.info ]);
  ...

<div data-filter="service">
  <div class="sign">Streaming service</div>
  <div class="item">Netflix</div>
  <div class="item">HBO Max</div>
  <div class="item">Hulu</div>
</div>
<div data-filter="genre">
  <div class="sign">Movie genre</div>
  <div class="item">Comedy</div>
  <div class="item">Action</div>
  <div class="item">Horror</div>
  <div class="item">Drama</div>
  <div class="item">Fantasy</div>
</div>

<li class="card" data-service="Netflix" data-genre="Comedy">

const cardSelector = '.card';
const hiddenCardClass = 'hidden';
const filterSelector = '[data-filter]';
const filterItemSelector = `${filterSelector} .item`;
const activeFilterItemClass = 'item_active';

document.querySelector('.filters').addEventListener('click', e => {
  const item = e.target.closest(filterItemSelector);
  if (!item) {
    return;
  }

  item.closest(filterSelector).querySelectorAll(filterItemSelector).forEach(n => {
    n.classList[n === item ? 'toggle' : 'remove'](activeFilterItemClass);
  });

  const values = Array.from(
    e.currentTarget.querySelectorAll(`.${activeFilterItemClass}`),
    n => [ n.closest(filterSelector).dataset.filter, n.innerText ]
  );

  document.querySelectorAll(cardSelector).forEach(n => {
    n.classList.toggle(hiddenCardClass, values.some(m => n.dataset[m[0]] !== m[1]));
  });
});

setup() {
    let isActive = false
    return {
        isActive
    }
},

methods: {
  onClick({ target: t }) {
    if (
      t.classList.contains('v-messages__message') &&
      t.closest('.v-messages.error--text')
    ) {
      // ну да, кликнули по сообщению об ошибке
    }
  },
},

Такое вообще возможно?

$items = array_combine(
  array_column($arr2['entries'], 'name_item'),
  $arr2['entries']
);

$keys = [ 'price_item', 'image_item' ];

foreach ($arr1 as $n) {
  foreach ($keys as $k) {
    $n[$k] = $items[$n[0]][$k];
  }

  $arr3[] = $n;
}

function updateValue(el) {
  el.value = el.value, из которого удалено всё, кроме цифр;
  el.dispatchEvent(new Event('input'));
  el.value = форматированное значение el.value;
}

function onInput(e) {
  if (e.isTrusted) {
    updateValue(e.target);
  }
}

Vue.directive('number', {
  bind(el) {
    el.addEventListener('input', onInput);
    updateValue(el);
  },
  update(el) {
    updateValue(el);
  },
  unbind(el) {
    el.removeEventListener('input', onInput);
  },
});

с минимальным количеством действий

return getValue(objectValus[prop], property);

const getValue = (obj, key) => Object
  .values(obj ?? {})
  .reduce((found, n) => found ?? getValue(n, key), obj?.[key]);

<div className={css.inputList}>
  {checkedList.map(n => (
    <div className={css.field} key={n}>
      <p>{n}:</p>
      <Input />
    </div>
  ))}
</div>

const total = results.reduce((acc, n) => acc + n.counts, 0);
const resultsObj = Object.fromEntries(results.map(n => [ n.id, n.counts ]));
const usersWithResults = users.map(n => ({
  ...n,
  result: (resultsObj[n.id] ?? 0) / total * 100,
}));

function solve(arr) {
  const last = arr.reduce((acc, n, i) => (acc[n] = i, acc), {});
  return arr.filter((n, i) => last[n] === i);
}

function solve(arr) {
  const last = new Map(arr.map((n, i) => [ n, i ]));

  arr.length -= arr.reduce((acc, n, i, a) => (
    a[i - acc] = n,
    acc + (i !== last.get(n))
  ), 0);

  return arr;
}

const solve = arr => (
  arr.splice(0, arr.length, ...[...new Set(arr.reverse())].reverse()),
  arr
);

const grouped = props.mainPage.room.reduce((acc, n) => (
  (acc[n.storey] ??= []).push(n),
  acc
), {});

{Object.entries(grouped).map(([ groupName, group ]) => (
  <div className="group" key={groupName}>
    <h3>{groupName}</h3>
    {group.map(n => <NumberRoom key={n.id} {...n} />)}
  </div>
))}

(function() {
  function func(arg) {
    console.log(arg, this);
  }

  let arg = 1;

  const f1 = () => func(arg);
  const f2 = func.bind(this, arg);

  arg = 2;

  f1();
  f2();
}).call('hello, world!!');

this.setState(({ todos }) => ({
  todos: todos.map((n, i) => i === index
    ? { ...n, isSuccess: true }
    : n
  ),
}));