Neat idea, but I'm not sure of its practicality. People typically don't stay on a single page for extended periods of time. So after setting up the javascript c

Neat idea, but I'm not sure of its practicality. People typically don't stay on a single page for extended periods of time. So after setting up the javascript compute client and transferring data, there wouldn't be time to run many actual tasks in most cases. Also of note, Facebook already kinda does this. They sometimes inject javascript into production pages to run load tests on new code behind the scenes.