Working in PHP I find I could probably easily download the PHP docs and be nearly completely happy. Client side though is a different story, plenty of times I have look for something in the JQuery docs but needed to refer to something like a stack overflow question to really get what I need.
JQuery/ JS seem to lend themselves to many different ways to do tasks and the selectors are a bit like regex for me in that I haven't really committed it all to memory.
It is a trade off though with the distractions, possibly you could try and bank up stuff that docs don't give you the answer to and hit them all up in one go.
Pretty much the full web dev stack is open source, including jQuery. If you really get stuck, you'll actually learn more by reading the source code than by getting a piecemeal info on Stackoverflow. I don't remember having to do that with jQuery (most of the JS I write is without a JS library, and I have the rhino book), but I've frequently read the source code to bits of Rails or MRI when I've not understood something and been offline.
Yeah you definitely can glean a fair bit from the source, something like selectors is fairly verbose though as it is a parser so often it's far quicker just to Google up the specific thing you need. You can also get a deeper understanding from the source so it does probably balance out.
JQuery/ JS seem to lend themselves to many different ways to do tasks and the selectors are a bit like regex for me in that I haven't really committed it all to memory.
It is a trade off though with the distractions, possibly you could try and bank up stuff that docs don't give you the answer to and hit them all up in one go.