always hilarious to see the dumb dependencies that these projects have https://github.com/sindresorhus/arrify https://github.com/JedWatson/classnames
While I can understand your skepticism on the first one, the second package is actually very useful. It doesn't just concatenate strings filtering out falsy values, it supports the whole old AngularJS class format. You can, for example, pass an object {string:booleanish} and it will add only the keys whose values are truthy. Pretty neat, actually.
> 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(" ")
}