But my biggest shift has been using these tools in a HAML/Less/Coffeescript environment, pre-compiling out the templates, CSS, and Javascript, and assembling them with r.js. I have a boilerplate Cakefile for doing this and use inotifywait to build on-demand as I code. Addy’s right that there is an embarrassment of riches out there at the library level, but the dev environment has also become powerful and useful too.

And I couldn’t figure out HOW to use Require.JS until ThomasDavis published the source code to his examples; once he showed me what worked, I was able to plug in my own code, and that made all the difference.

Local variable creation is more of a parsing activity than an execution activity, you don’t need to know about it at all, so it doesn’t really make sense to move any of your declarations just for that reason. (For other reasons, maybe.)

Using the var keyword just declares the scope of the variable, nothing else. Nothing is ‘moved’, the variable is bound to the function’s activation object by the parser (just like the function’s parameter arguments). As long as you understand there is only program scope and function scope, there’s no confusion at all.

Some people prefer to declare all the variables at the top of their scope as a form of data dictionary, which is fine, but for temporary variables, one might wish to declare them closer to where they are first initialised (e.g. within loop initialisers) this follows the Don’t Repeat Yourself principle more closely, if the variable cannot be initialised early (separating the declaration and initialisation unnecessarily is avoidably repeating yourself).