Never underestimate the CPU power of 1000's of mobile devices running a high level, yet highly optimized, Turing complete language. So you don't trust the clie

Never underestimate the CPU power of 1000's of mobile devices running a high level, yet highly optimized, Turing complete language. So you don't trust the client and still need to do validation on the server, fine at least you can avoid sending invalid requests to the server and give the user instant feedback. So you want to render a partial change to your page, have the server render a bunch of HTML from a database, or serialize the data minimally and have the client render the HTML. What about rendering visualizations of your data, chart, graphs etc, server rendering and sending jpegs, or client using canvas/svg? Nice to have that choice.