JavaScript does not have a monopoly in web browsers. Microsoft supported vbScript and Google made a better and faster JavaScript (Dart) which also ran natively in the browser. But neither didn't take off. You can still "compile" for the browser though, the funny thing is that a lot if not most of the code running on the most popular web sites has gone through at least one compile step. So people don't actually program in JavaScript, it has become more of a compilation target.