These sites offer references and guides to JavaScript as a language in general, rather than jQuery in particular.
This site has a comprehensive JavaScript reference, a guide to programming with JavaScript, links to helpful tools, and more: http://developer.mozilla.org/en/docs/JavaScript/.
This online book provided by Sun is "a reference manual for the JavaScript language, including both core and client-side JavaScript for version 1.3": http://docs.sun.com/source/816-6408-10/contents.htm.
The Microsoft Developer Network (MSDN) JScript Reference provides descriptions of the full set of functions, objects, and so on. It's especially helpful for understanding Microsoft's implementation of the ECMAScript standard in Internet Explorer: http://msdn.microsoft.com/en-us/library/x85xxsf4(VS.71).aspx.
Additionally, the MSDN, HTML, and DHTML reference provides descriptions of collections, events, constants, methods, objects, and properties in the DHTML Object Model. As with the JScript Reference, it can be especially useful for cases in which Internet Explorer deviates from the standard or Internet Explorer's interpretation of an ambiguous specification differs from that of other major browsers: http://msdn.microsoft.com/en-us/library/ms533050%28VS.85%29.aspx.
While focused primarily on its own browser platform, Opera's site for web developers includes a number of useful articles on JavaScript: http://dev.opera.com/articles/.
Peter-Paul Koch's Quirksmode site is a terrific resource for understanding differences in the way browsers implement various JavaScript functions, as well as many CSS properties: http://www.quirksmode.org/.
Matt Kruse's JavaScript Toolbox offers a large assortment of homespun JavaScript libraries, as well as sound advice on JavaScript best practices and a collection of vetted JavaScript resources elsewhere on the Web:
This page includes a very lengthy list of questions frequently asked on the comp.lang.javascript Usenet group, along with answers and links to further information: http://www.jibbering.com/faq/.