gistfile1.txt

let str = ")((()))()";
let count = 0;

function findMatch(str) {
  if (str.includes("()")) {
    let index = str.indexOf("()");
    str = str.slice(0, index) + str.slice(index + 2);
    count++;
    findMatch(str);
  } else {
    console.log(count);
    return;
  }
}

findMatch(str);