Pattern Matcher

Given a pattern and a string s, find if s 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 s.

/**
 * @param {string} pattern
 * @param {string} s
 * @return {boolean}
 */
var wordPattern = function(pattern, words) {
    const wordsArr = words.split(" ");
    const patternMap = {}
    let isMatch = true;
    const prevUsedWords = []
    
    // if more/less words than letters in pattern
    if(wordsArr.length !== pattern.length){
        return false;
    }
    
    for(let i = 0; i < pattern.length;i++){
        
         // haven't come across this letter in pattern yet
        if(!patternMap[pattern[i]]){
            
            // make sure it is not equal to other pattern words
            if(prevUsedWords.includes(wordsArr[i])){
                isMatch = false;
                break;
            }
            
            // if new word... set it and save it to current word
            patternMap[pattern[i]] = wordsArr[i];
            
            // add word to previous words list
            prevUsedWords.push(wordsArr[i])
            
        } else if(patternMap[pattern[i]]!==wordsArr[i]) {
            
            // else we have come across it but it doesn't match previous value
            isMatch = false
            break;
        }
    }
    return isMatch;
};