Question Eleven - Valid Parenthesis

Given a string containing just the characters'(',')','{','}','['and']', determine if the input string is valid.

The brackets must close in the correct order,"()"and"()[]{}"are all valid but"(]"and"([)]"are not.

Solution

/**
 * @param {string} s
 * @return {boolean}
 */
var isValid = function(s) {
  var stack = [];
  var pairs = {'(': ')', '{':'}', '[': ']'};
  var cur,
  i,
  stackTop;

  for(i = 0; i < s.length; i++){
    cur = s.charAt(i);
    if(pairs.hasOwnProperty(cur)){
      stack.push(cur);

    }else if(stack.length === 0){
      return false;
    }else{
      stackTop = stack.pop();
      if(pairs[stackTop] !== cur){
        return false;
      }
    }

  }

  if(stack.length === 0){
    return true;
  }else{
    return false;
  }

};

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