Four-five years ago there was a crossroad that in reflection I screwed up on. I was so sure that PrototypeJS was the right library to invest in, it made working with multi-browser javascript a breeze & had a plethora of fantastically useful helper functions. Now, present day, its been almost three years of non-stop jQuery and I’m kind of fine with that. Though a mere shadow of the power that is ExtJS, jQuery UI is a semi-decent library for widgets and asthetics, jQuery itself does what I need, and I don’t get looks of WTF when I mention I’m using jQuery over Prototype at the local developer meetups.