Its amazing how many programmers in the greater community of programmers ask questions like "How do I do an EXTJS backend?" or "How do I integrate jQuery with Java?", not understanding the distinction between the client and the server. Then I got to thinking, are there frameworks where the server actually sends JS or something to the client to be executed? What are philosophical thoughts around such approaches?
edit -- to clarify:
im not asking if its possible, I am asking if its a good strategy or frownded upon. I am not asking if client side languages can run on the server. I am asking if there are frameworks that are built around dynamically serving dynamic client side code.
Many different frameworks do this, when you're doing ASP.NET work, you'll constantly be seeing POSTBACK calls in the client, this is generated by the framework and is a Javascript call. In the Java world, most JSF frameworks to this to a greater or lesser extent. I see no harm in this as long as you remember the "never trust the client" rule. So if you are going to do a field validation in Javascript on the client, that does NOT release you from having to do the same check on the server end. I did a largish Flex application not too long ago, and as part of it I started down the road of creating a module that would read Hibernate Validation annotations and automagically create the same validation on the Actionscript, deadlines killed that before I got too far, but I do like the idea of being able to set validations once on the back end and have them checked on the client, saving the round-trip to the server.