Balanced parenthesis problem

paren.js

var open = ["(", "{", "["];
var closed = [")", "}", "]"];

function isMatched(str) {
  var stack = [];
  if (str === null || str === undefined) return false;
  if (str.length == 1 ) return false;
  
  for (var i = 0; i < str.length; i++) {
      var character = str[i];
      var openIndex = open.indexOf(character);
      var closedIndex = closed.indexOf(character);
      
      if (openIndex >= 0) {
        stack.push(character);
      } else if (closedIndex >= 0){
        
        var match = open[closedIndex];
        if (stack.pop() != match) {
          return false;
        }
      } else {
        // Determine what to do here.
        // Ask if we should consider non parenthesies as
        // a failure state or ignore them.
        return false;
      }
  }
  
  // If we have all open or all closed, this will catch
  // that state.
  return stack.length == 0;
}

console.log(isMatched("[{({})}]"));
console.log(isMatched("[[{{({)}}]]"));
console.log(isMatched("("));
console.log(isMatched("(("));
console.log(isMatched("(A)"));