bracket-parse.js

bracketParse = str => {
  let cursor = 0;
  let depth = 1;
  const stack = [];
  const subStack = [];

  while (cursor < str.length) {
    const si = str.indexOf('(', cursor);
    const nsi = str.indexOf('(', si + 1);
    const ei = str.indexOf(')', cursor);
    cursor = si;

    if (si > ei || (si >=0 && ei === -1) || (si === -1 && ei >= 0)) throw 'Invalid braket!';
    if (ei === -1) return stack;
    if (si === -1 || nsi === -1 || nsi > ei) {
      stack.push({depth, start: si, end: ei});
      cursor = ei + 1;

      while (subStack.length) {
        const nsi = str.indexOf('(', cursor);
        const ei = str.indexOf(')', cursor);
        if (nsi === -1 || nsi > ei) {
          depth -= 1;
          const {startIndex: si} = subStack.pop();
          stack.push({depth, start: si, end: ei});
          cursor = ei + 1;
        } else {
          
          break;
        }
      }
    } else {
      subStack.push({depth, startIndex: si});
      depth += 1;
      cursor += 1;
    }
  }
  return stack;
};
bracketParse('123(te(s(t)(t)e)st)1234');