Dealing with Kotlin as a front-end language and then mixing it with a lot of existing libraries from JS can be a problem if you intend to publish your library to others. I'm not saying that Kotlin is a bad choice, but the contrary. Kotlin is an amazing language and it's very pleasant to code in it. But we already have a lot of good libraries written in JS today and most of these libraries can make your life a lot better if you are writing a web application. If you are a front-end developer you know what I mean. We have a lot of amazing libraries and frameworks like React, Aurelia, Angular, VueJS, Marko, RxJS etc. Then what is the problem? Well, Kotlin compilation to JS is getting better and better, but it's not a language that comes from the Web environment but from the JVM (Java Virtual Machine). And because of that, while you can make a lot of good things with it, you still have to deal with not only the JS nightmare of tooling to bundle and distribute your transpile