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.
As web pages become more and more like applications, code performance becomes more and more important. This article looks at a number of performance issues to avoid, in EcmaScript, DOM and AJAX requests. Covers eval, the with keyword, try/catch in performance-critical code, global variables, implicit object conversion, string concatenation, primitive operations over function calls, repainting and reflowing documents, modifying elements, using XPath.