Ivo Wetzel covers some of the quirks of the JavaScript language. Some of these cause subtle bugs, some overturn conventional wisdom. It covers toString on numbers. Covers the advanced JavaScript features such as prototypal inheritance, this, closures, anonymous wrappers, type-casting, automatic semicolon insertion and hoisting of function and variable declarations.
Douglas Crockford explains the new strict mode introduced in the 5th edition of ECMAScript. It is an opt-in mode that repairs or removes some of the language's most problematic features such as: function scoping, implied global variables and global leakage, read-only variable failures, octal defaults and function arguments.
Tim Caswell describes the JavaScript variable 'this', which is about current scope and current context. The only way to create scope in JavaScript is through function definitions, and in most cases the context is the receiver of the message (the object before the dot in the method call). He also talks about approaches to controlling what this references with call, apply and bind.