単語の配列から最頻出の単語を返す

modalWord.js

function modalWord(words) {
    // words = words.map(function(s) { return s.toLowerCase(); }); // nomalize
    var counter = {};
    words.forEach(function(str){
        if(counter.hasOwnProperty(str)) {
            counter[str]++;
        } else {
            counter[str] = 1;
        }
    });

    var maxCount = 0;
    var modal;

    for (var keyStr in counter) {
        if (maxCount === 0) {
            modal    = keyStr;
            maxCount = counter[keyStr];
        } else {
            if (counter[keyStr] > maxCount) {
                modal    = keyStr;
                maxCount = counter[keyStr];
            }
        }
    }
    return modal;
}