Word Pattern.js

/*Given a pattern and a string str, find if str follows the same pattern.

Here follow means a full match, such that there is a bijection between a letter in pattern and a non-empty word in str.

Examples:
pattern = "abba", str = "dog cat cat dog" should return true.
pattern = "abba", str = "dog cat cat fish" should return false.
pattern = "aaaa", str = "dog cat cat dog" should return false.
pattern = "abba", str = "dog dog dog dog" should return false.
Notes:
You may assume pattern contains only lowercase letters, and str contains lowercase letters separated by a single space.*/

/**
 * @param {string} pattern
 * @param {string} str
 * @return {boolean}
 */

var wordPattern = function(pattern, str) {
    words = str.split(" ")
    if(pattern.length != words.length)
        return false

    pattern_map = {}
    word_map = {}
    for(i=0; i<pattern.length; i++){
        if(pattern_map[pattern[i]] != word_map[words[i]])
            return false
        pattern_map[pattern[i]] = i
        word_map[words[i]] = i
    }

    return true
};