It depends what you mean - if you only mean "learn JavaScript" in the sense of learning the language itself, then no, jQuery doesn't change a thing, you've still got to figure out your way around the (rather minimalistic, esp. given the lack of significant standard libraries) language.
But if you mean "learn JavaScript" in the pre-jQuery sense, then what you really mean is "accumulate encyclopedic knowledge of all sorts of browser dependent bullshit that constantly thwarts every attempt to write clean, reusable code that actually works." In that case, jQuery (and other similar libs, of course) really does change the game. You can get pretty damn far without ever knowing a thing about the various incompatibilities; this, IMO, is one of the best things about the new sets of Javascript tools out there, they really are starting to bring us towards the point where you can just write clean code that does what it's supposed to, without working around bugs (features?) in other people's code.
>> "accumulate encyclopedic knowledge of all sorts of browser dependent bullshit that constantly thwarts every attempt to write clean, reusable code that actually works."
That point is overplayed to the point of insanity. Unless you're targeting IE5, browser differences in js are minimal. Most of the inconsistencies are in layout.
But if you mean "learn JavaScript" in the pre-jQuery sense, then what you really mean is "accumulate encyclopedic knowledge of all sorts of browser dependent bullshit that constantly thwarts every attempt to write clean, reusable code that actually works." In that case, jQuery (and other similar libs, of course) really does change the game. You can get pretty damn far without ever knowing a thing about the various incompatibilities; this, IMO, is one of the best things about the new sets of Javascript tools out there, they really are starting to bring us towards the point where you can just write clean code that does what it's supposed to, without working around bugs (features?) in other people's code.