In below code, when I change input A as an user; sometimes the code won't reflect so until I have changed b as well; and at times; it won't show change at all; why?
the renderUI code you provided is not shown to be dependent (i.e. would change) on anything.
the req() implies some possible inputs it may change on but we cant guess.
I suppose the question to ask you to prompt your thinking is, what have you done to make output$X changeable on input A ? what you've just shown is that its responsible for presenting input A ; you should be cautious in such contexts of infinite loops. code that depends on itself so that its changing causes itself to change which causes itself to change ,and on forever in a loop.