ReCn 
Blazing fast. Tiny size. The last one className helper.
Usage
npm i -S recn
import { cn } from 'recn';
const cat = cn('Cat');
cat(); // Cat
cat({ size: 'm' }); // Cat_size_m
cat('Tail'); // Cat-Tail
cat('Tail', { length: 'small' }); // Cat-Tail_length_small
const dogPaw = cn('Dog', 'Paw');
dogPaw(); // Dog-Paw
dogPaw({ color: 'black', exists: true }); // Dog-Paw_color_black Dog-Paw_exists