reverseParethensesContent.js

/**
console.log(deepReverse('a1(b2(c1))a1')); // => a1(2b(1c))a1
**/
  var string = '1a(2b(c1))a1';

function deepReverse(string, deep){
  var length = string.length;
  var i = 0;
  var collect = [];
  var deep = deep || false;
  while(i < length) {
    if (string[i] === '(') {
      var returned = deepReverse(string.substr(i+1), true);
      collect.push([].concat('(',returned).join(''));
      // skip the returned length 
      i += returned.length ;
    } else if (string[i] === ')' && deep) {
      return collect.join('');
    } else {
      if (deep) {
        collect.unshift(string[i]);      
      } else {
        collect.push(string[i]);             
      }

    }
    i++;
  }
  return collect.join('');
}