A clever hands-on interactive mini-course by Nathan Whitehead that guides you through bite-sized chunks from variables, to functions, to return values, to functions as first-class objects and right into closures and finally continuations. The hands-on exercises are JS Linted and unit-tested which gives you ample space to try out your new-found knowledge.
Exploring the features of Firebug, with code examples covering using the console, timing code, stack traces, debugging and breakpoints, profiling, tracing HTTP requests. An excellent overview of Firebug's functionality
A BetterExplained article that discusses how to reduce the initial load time of JavaScript files. Covers measuring load times, and a number of approaches to delaying the loading of a JavaScript file. Also covers minifying JavaScript and maintaining a debug version of code. Also covers an AJAX onLoad pattern to dynamically include JavaScript after page load, and HTTP caching of external JavaScript files
Douglas Crockford's presentation on Advanced JavaScript. He covers topics such as inheritance, modules, debugging, efficiency and JSON.
Douglas Crockford examines the need for minimising the size of JavaScript code and compares minification and obfuscation. Obfuscation has the side-effect of introducing bugs because it changes variable names. The recommended approach is minification along with GZip compression. Since JavaScript is sent along in source form, it is impossible to hide that from a determined hacker
First in a series of talks from Douglas Crockford about the JavaScript language. These talks cover the JavaScript language, from the history, the language, advanced features, platforms, standards and programming style. Talks about inheritance, using functions to build objects, closures, as well as the basic JavaScript syntax. Also covers code conventions. JavaScript is a language that requires discipline.
Christian Heilmann describes an approach to building complex web application by basing them around events, particularly around YUI's CustomEvent class.
Joe Hewitt, in this Dr Dobbs article talks about using the Firebug extensions to inspect and debug Ajax applications (or any browser-based JavaScript application). It also has CSS inspecting capabilities, editing JavaScript on the fly, inspecting HTTP request and responses, logging, breakpoint debugging and profiling. A useful howto.
Svend Tofte puts together a detailed guide to setting up and using the Venkman debugger. From basic debugging to watchlists and call stacks, breakpoints, and more advanced techniques like meta comments and profiling. It also contains a list of other useful Venkman resources.