In the “Dependencies” section of the article, Stefanov describes using the onLoad or onReadyStateChange events of the dynamically generated script tag to receive notification when that script has been loaded by the browser. Once you know it’s loaded, then you know it’s safe to begin using the code it contains.
This works great for Firefox and IE, but fails completely in the Safari browser. Safari doesn’t implement onLoad notifications for script tags. This forces you to abandon the onLoad technique and instead use the technique of embedding something at the end of each script file to signal when the file has been loaded.
The script libraries for the Windows Live sites use this technique – every source file contains a function call at the bottom that tells a central notifier that it has been loaded. Other code can ask the notifier to signal them when a file or set of files have been loaded. This works in all browsers without relying on diverging browser idiosyncracies.