var paren = "(()())(())(()(()))";
var result = "";
var cur = "";
var counter = 0;
for(i=0;i<paren.length;i++)
{
if(paren[i] === '(')
{
counter++;
if(counter > 1){
cur += '(';
}
}else{
counter--;
if(counter === 0){
result += cur;
cur = "";
}else{
cur += ')';
}
}
}
console.log(result);