Maximum Score From Removing Substrings LeetCode solution in JavaScript

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var maximumGain = function (s, x, y) {
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  const n = s.length;
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  let totPoints = 0;
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  let stack;
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  if (x > y) {
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    stack = remove(s, x, "ab");
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    s = stack.join("");
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    remove(s, y, "ba");
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  } else {
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    stack = remove(s, y, "ba");
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    s = stack.join("");
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    remove(s, x, "ab");
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  }
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  return totPoints;
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  function remove(str, points, match) {
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    const stack = [];
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    for (let i = 0; i < str.length; i++) {
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      const char = str.charAt(i);
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      if (stack.length > 0 && stack[stack.length - 1] + char == match) {
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        totPoints += points;
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        stack.pop();
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      } else {
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        stack.push(char);
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      }
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    }
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    return stack;
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  }
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};