javascript dotify object

1function dotify(obj) {
2    const res = {};
3    function recurse(obj, current) {
4        for (const key in obj) {
5            const value = obj[key];
6            if(value != undefined) {
7                const newKey = (current ? current + '.' + key : key);
8                if (value && typeof value === 'object') {
9                    recurse(value, newKey);
10                } else {
11                    res[newKey] = value;
12                }
13            }
14        }
15    }
16    recurse(obj);
17    return res;
18}
19dotify({'a':{'b1':{'c':1},'b2':{'c':1}}}) //{'a.b1.c':1,'a.b2.c':1}