Codility: Brackets Solution

1function Stack() {
2  stack = []
3
4  this.push = function (el) {
5    stack.push(el)
6  }
7
8  this.pop = function () {
9    return stack.pop()
10  }
11
12  return {
13    ...this,
14    get size() {
15      return stack.length
16    },
17    get head() {
18      return stack[this.size - 1]
19    },
20  }
21}
22
23function solution(S) {
24  const isOpen = c => "{[(".includes(c)
25  const closeOf = c =>
26    ({
27      "{": "}",
28      "[": "]",
29      "(": ")",
30    }[c])
31  const chars = S.split("")
32  const stack = new Stack()
33  chars.forEach(c => {
34    if (isOpen(c)) {
35      stack.push(c)
36    } else if (c === closeOf(stack.head)) {
37      stack.pop()
38    } else {
39      stack.push(c)
40    }
41  })
42  return stack.size === 0 ? 1 : 0
43}