Comment by anonytrary

> You can, for example, pass an object {string:booleanish} and it will add only the keys whose values are truthy.

Why is this something you can't do on your own in a few lines of code?

  const classNames = (o, c=[]) => {
    for (let k in o) if (o[k]) c.push(k) // booleanish
    return c.join(" ")
  } 

This is not cool at all! Why import a trivial function over NPM to do this for you? Better to lower your dependency count and have a "util.js" file for helpers like this.