Js 集合运用

<script type="text/javascript">
        var arrObj = [];
        var str = ‘good‘;
        var arr = str.split(‘‘);
        for (var i = 0; i < arr.length; i++) {
            var _j = -1;
            for (var j = 0; j < arrObj.length; j++) {
                if (arrObj[j].key == arr[i]) {//判断数组中是否已存在该字符串
                    _j = j;
                }
            }
            var num = arrObj[_j] != null ? (arrObj[_j].value + 1) : 1;
            if (_j != -1) { arrObj.splice(_j, 1); }
            arrObj.push({ key: arr[i], value: num });
        };

        for (var z = 0; z < arrObj.length; z++) {
            document.write(arrObj[z].key + arrObj[z].value);
        }
    </script>