[JavaScript] 올바른 괄호

function solution(s){
    var answer = true;
    var stack = [];
    if(s.length%2===1) return false;
    for(var i =0;i<s.length;i++){
        if(s[i]=='('){
            stack.push(1);
        }else if(stack.length==0){
            return false;
        }else{
            stack.pop();
        }
    }
    if(stack.length!==0) return false;
    return answer;
}