0xD34F

const digitsOnly = str => str.replace(/\D/g, '');

// или

const digitsOnly = str => (str.match(/\d/g) ?? []).join('');

// или

const digitsOnly = str => ''.concat(...str.matchAll(/\d/g));

// или

const digitsOnly = str => str.split(/\D/).join``;

// или

const digitsOnly = str =>
  Array.prototype.reduce.call(
    str,
    (acc, n) => acc + ('0123456789'.includes(n) ? n : ''),
    ''
  );

document.querySelectorAll('span').forEach(n => {
  n.innerText = digitsOnly(n.innerText);
});

// или

for (const n of document.getElementsByTagName('span')) {
  n.textContent = digitsOnly(n.textContent);
}

if (state) {
  this.x = 'c';
} else if (route) {
  this.x = 'b';
} else if (prop) {
  this.x = 'a';
}

this.x = [
  [ state, 'c' ],
  [ route, 'b' ],
  [  prop, 'a' ],
].find(n => n[0])?.[1] ?? this.x;

this.x = 
  state ? 'c' :
  route ? 'b' :
  prop  ? 'a' :
          this.x;

switch (true) {
  case !!state: this.x = 'c'; break;
  case !!route: this.x = 'b'; break;
  case  !!prop: this.x = 'a'; break;
}

mounted () {
  ...

watch: {
  showModal(val) {
    $(this.$refs.modal).modal(val ? 'show' : 'hide');
  },
},

const type = x => x == null ? x : x.constructor;

type() === undefined // true
type(null) === null // true
type(/./) === RegExp // true
type(666) === Number // true
type(type) === Function // true

const typename = x => x?.constructor.name ?? `${x}`;

typename() // 'undefined'
typename(null) // 'null'
typename(false) // 'Boolean'
typename(187) // 'Number'
typename('hello, world!!') // 'String'
typename(/./) // 'RegExp'
typename({}) // 'Object'
typename([]) // 'Array'
typename(document.body) // 'HTMLBodyElement'
typename(document.getElementsByClassName('xxx')) // 'HTMLCollection'
typename(new class XXX {}) // 'XXX'
typename(typename) // 'Function'

const newArr = arr.reduce((acc, n, i) => (acc.push(n + (acc[i - 1] ?? 0)), acc), []);

// или

const newArr = arr.reduce((acc, n) => (acc[0].push(acc[1] += n), acc), [ [], 0 ])[0];

// или

const newArr = arr.map((n, i, a) => eval(a.slice(0, i + 1).join('+')));

// или

const newArr = arr.map((n, i, a) => a.reduce((acc, m, j) => acc + m * (j <= i), 0));

например на body

methods: {
  onClick() {
    document.body.classList.toggle('active');
  },
},

computed: {
  headerClass() {
    return в зависимости от this.$route;
  },
},

{reviews.map(n => (
  ...
  {Array.isArray(n.children) && n.children.length ? <Reviews reviews={n.children} /> : null}
  ...
))}

methods: {
  onKeyPress(e) {
    if (/* нажато что надо */) {
      this.$refs.searchInput.focus();
    }
  },
},
created() {
  document.addEventListener('keypress', this.onKeyPress);
  this.$on('hook:beforeDestroy', () => document.removeEventListener('keypress', this.onKeyPress));
},

('0' + date.getMonth()).slice(-2)
// или
`${date.getMonth()}`.padStart(2, 0)

date.toLocaleDateString('ru-RU').split('.').reverse().join('.')
// или
date.toLocaleDateString('ru-RU').replace(/(\d+)(\.\d+\.)(\d+)/, '$3$2$1')

this.props.options

return X; // тут НУЖНО ...

return new Promise(resolve => {
  const img = new Image();
  img.onload = () => resolve(true);
  img.onerror = () => resolve(false);
  img.src = 'тут ссылка на изображение';
});

$('.block__holder').on('click', '.block__image', function() {
  const $this = $(this);
  $this.addClass('block__image--active').siblings().removeClass('block__image--active');
  block_slider.trigger('to.owl.carousel', $this.index());
});

document.querySelector('.menu').addEventListener('click', ({ target: t }) => {
  if (t.tagName === 'A') {
    const submenu = [...t.parentNode.children].find(n => n.classList.contains('sub-menu'));
    if (submenu) {
      submenu.classList.toggle('red');
    }
  }

  // или

  if (t.matches('a')) {
    t.parentNode.querySelector(':scope > .sub-menu')?.classList.toggle('red');
  }
});

for (const n of document.querySelectorAll('.menu a')) {
  n.addEventListener('click', onClick);
}

function onClick() {
  this.nextElementSibling?.classList.toggle('red');
}

// или

document.querySelectorAll('.sub-menu').forEach(function(n) {
  n.previousElementSibling.addEventListener('click', this);
}, e => e.target.nextElementSibling.classList.toggle('red'));