LeetCode: Score Of Parentheses Solution

1/**
2 * @param {string} S
3 * @return {number}
4 */
5var scoreOfParentheses = function (S) {
6  const resStack = [0] // default for empty string
7
8  for (const paren of S) {
9    if (paren === "(") {
10      resStack.push(0)
11    } else if (paren === ")") {
12      const top = resStack.pop()
13      const res = top > 0 ? top * 2 : 1
14      resStack[resStack.length - 1] += res
15    }
16  }
17
18  return resStack.pop()
19}