I think this is an important question to ask. I don't think the OP is asking it for quite the right reasons, but I still think it's important. As web developer

I think this is an important question to ask. I don't think the OP is asking it for quite the right reasons, but I still think it's important. As web developers, we're all about 'openness', 'choice' and other warm fuzzy concepts. So why is it OK that JavaScript is the only client side option? the script element has 'language' and 'type' attributes, clearly indicating the possibility of other types of script (indeed, microsoft used to support VBScript in web pages, don't know if they still do). To address some of your points: 1) Implementation isn't important. Sure, don't ship binaries to browsers. That's just a detail, the main point is why can't we ship anything other than JS? 3) JS is a cool language. So what? JPG is a cool format, doesn't mean there's no room for PNG too. 4) If all you have is JavaScript then everything looks like a JS problem.