JavaScript is not one thing. JavaScript is many things. It's the way that different companies can work together with interoperability. It's the way to be backward compatible for the sake of supporting millions of applications that you could never begin to refactor when introducing some incompatible change. It's the way to give the browsers a way to be programmed beyond what is possible with just HTML and CSS. And on it goes.

Let's take just an issue that will always be annoying: different systems. OK, they are different, they are created by different companies even. How can a single tool support the different systems? If any alternative to JavaScript had the aspiration to one-up JavaScript, said tool would have to start to answer that question, if not solve it completely.

Software development grew from the needs of companies supporting the Windows operating system and Unix-like systems. One of the problems that always bothered Microsoft in software development was that they had the goal of protecting their Windows above nearly all else. Sometimes it didn't work, since some small cool features that Windows developers created for some other system such as "AJAX" for the browser ended up causing more competition to Windows after a while. So the goal of protecting Windows above all else was not always achieved. There is a saying that information wants/needs to be free. If software is like information, it too wants to be free. It doesn't belong to a single niche of a system.

I think that where we are at is in many ways thanks to Microsoft. For the good and for the bad. If Microsoft didn't have to defend their Windows so much, perhaps they would have built more of a sandbox for applications. Even if the sandbox could have allowed for competitors to emulate it for their own systems and then applications would not be stuck at the latest version of Windows, necessarily. Think for example all the effort they put into making DirectX a Windows-only thing.

So we have ended up with JavaScript. Which even Microsoft seems to be taking some joy in supporting lately. It looks like way too many companies have simply settled on JavaScript for now to want more change. Better the evil that you know than the evil that you don't know. The worse is better and all that jazz. :-)

Some googlers have tried to come up with an alternative to JavaScript in Dart. But given that JavaScript is many things, their fight continues. They have another shot if Dart ends up powering mobile devices like Android. It is that fight that an alternative to JavaScript needs to support many different systems.