Codility: Nesting 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  }
18}
19
20function solution(S) {
21  const chars = S.split("")
22  const stack = new Stack()
23  chars.forEach(c => {
24    if (c === "(") {
25      stack.push(c)
26    } else {
27      const head = stack.pop()
28      if (head === "(") {
29        return
30      }
31      stack.push(c)
32    }
33  })
34  return stack.size === 0 ? 1 : 0
35}