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.
Douglas Crockford's presentation on Advanced JavaScript. He covers topics such as inheritance, modules, debugging, efficiency and JSON.
Instead of creating a new XmlHttpRequest object for every request, this post provides code to pool these objects together and reuse them. This saves a great deal of processing times, particularly in IE.
A collection of performance related techniques, including temporary references (for deeply namespaced properties), optimising loops by referencing the collection length once, reasons to avoid the with syntax, using null over the delete function, comparison for equality and identity and short-circuit logical expressions