idkw13

В чем моя ошибка?

const sum = val =>
  val instanceof Object
    ? Object.values(val).reduce((acc, n) => acc + sum(n), 0)
    : typeof val === 'number'
      ? val
      : 0;


console.log(sum(obj));

function sum(val) {
  let result = 0;

  for (const stack = [ val ]; stack.length;) {
    const n = stack.pop();
    if (n instanceof Object) {
      stack.push(...Object.values(n));
    } else if (n === +n) {
      result += n;
    }
  }

  return result;
}

const parseValue = str => {
  const values = str.match(/[^\s,]+/g) || [ null ];
  return values.length > 1 ? values : values[0];
};

const parseStyleStr = str =>
  str.split(';').reduce((acc, n) => {
    const [ k, v ] = n.split(':').map(n => n.trim());
    if (k && v) {
      const f = [...v.matchAll(/([\w]+?)\((.+?)\)/g)];
      acc[k] = f.length
        ? Object.fromEntries(f.map(n => [ n[1], parseValue(n[2]) ]))
        : parseValue(v);
    }

    return acc;
  }, {});

.opacity {
  opacity: 0.4;
}

const $items = $('.menu__item')
  .mouseenter(e => $items.not(e.target).addClass('opacity'))
  .mouseleave(e => $items.removeClass('opacity'));

Задача - создать онлайн кинотеатр.

const XXX = length => Array
  .from({ length }, (n, i) => Array
    .from({ length: i + 1 }, (n, i) => i + 1)
    .join(','))
  .join('\n');

console.log(XXX(5));

const XXX = length => Array
  .from({ length }, function() {
    this.push(-~this.length);
    return this.join`,`;
  }, [])
  .join`\n`;

const XXX = length => Array
  .from({ length }, (n, i) => Array
    .from(Array(++i).keys())
    .reduce((acc, n) => acc + (acc && ',') + ++n, ''))
  .reduce((acc, n) => acc + (acc && '\n') + n, '');

function sortChildren(el, key) {
  el.append(...Array
    .from(el.children, n => [ n, key(n) ])
    .sort((a, b) => a[1] - b[1])
    .map(n => n[0])
  );
}


sortChildren(document.querySelector('.menu'), n => +n.dataset.num);

.main__title {
   padding-top: 1.25rem;
   color: #ffffff;
   font-weight: 400;
   width: 100%;
}

.main__container {
   display: flex;
   flex-direction: row;
   flex-wrap: wrap;
}

const result = ind.reduce((acc, col) => {
  arr.forEach((n, i) => {
    acc[i].push(i ? n.filter((m, j) => arr[0][j] === col) : col);
  });
  
  return acc;
}, arr.map(() => []));

const indObj = Object.fromEntries(ind.map((n, i) => [ n, i ]));
const result = arr.reduce((acc, n, i) => (
  i && n.forEach((m, j) => acc[i][indObj[arr[0][j]]].push(m)),
  acc
), arr.map((_, i) => ind.map(n => i ? [] : n)));

const result = Object.values(arr.reduce((acc, n) => (
  (acc[n.ID] = acc[n.ID] || { ID: n.ID })[n.FIELD] = n.VALUE,
  acc
), {}));

var a = 1,x; // a = 1
x = 
++a // a = 2 
+ 
++a; // a = 3
// x = 5, x = 2 + 3
// a = 3, последняя операция ++a

x +=a; // x = 8, x = 5 + 3

console.log(x); //8