Word Pattern Algo

wordPatternAlgo.js

var wordPattern = function(pattern, str) {
 
  var letters = pattern.split('');
  var symbols = {};
  var reverseSymbols = {};
  var words = str.split(' ');
  if (letters.length != words.length) return false;
  
    for (var i = 0; i < letters.length; ++i) {
     var word = words[i];
     var letter = letters[i];
     var symbol = symbols[letter];
     
      if (symbol === undefined) {  
       symbols[letter] = word;
       symbol = word;
       if (reverseSymbols[word]){
         return false;
       }
       reverseSymbols[word] = letter;
      }
      //console.log(symbol, word, letter);
     if (symbol != word) return false;
    }
  return true;
};

// true
// var pattern = "abba";
// var str = "dog cat cat dog";

// false
// var pattern = "abba";
// var str = "dog cat cat fish";

//false
// var pattern = "aaaa";
// var str = "dog cat cat dog";

//false
var pattern = "abba";
var str = "dog dog dog dog";

console.log( wordPattern(pattern, str) );