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.
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
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.
Douglas Crockford's useful utility that looks for potential problems in JavaScript code. Produces warnings like improper use of eval, and places where a dot operator is better than an array-like reference. An excellent tool to use before running JavaScript through a minifier. JSLint is actually a JavaScript parser written in JavaScript