I use JavaScript because you have to. To be honest I avoided it for quite a long time because I had some bad experiences with it a decade or so ago. I would implement as much functionality as I could server-side, and reserve client-side JS for code which absolutely must be run client-side, (i.e. animations). However, with the advent of ES2015+ and tools like Babel getting rid of some of the lexical scoping headaches and allowing me to write code more like what I'm familiar with I've been a lot more open to working with and writing JavasScript. I've even come to terms with the idea of putting as much functionality as possible into the front-end in order to achieve useable mobile-first offline functional progressive web apps.