Question: I have a number of projects that could benefit from JavaScript. I've seen a lot of "Oh, you can use JavaScript for that!", but little detail about how and where that's done. Does the script live on a server somewhere or is it just embeded with a cut-and-paste via the "edit HTML source" button?

Looking for some guidance on the best place within the sites/farms from which to run scripting.

Answer: 
There are several ways to add JavaScript to SharePoint. You could add directly or reference it into the masterpage, page layout, code behind etc.. The script lives always on a server, because it serves it. 

Keep in mind that JavaScript is different language to learn and can be very powerful. Therefor I recommend learning it:

<http://www.codecademy.com> (Nice website where you can learn the fundamentals)
<https://developer.mozilla.org/en/JavaScript/Guide> (Very comprehensive information)

Besides learning the language it's recommended to place JavaScript into files, so you can reuse and manage your code. The **Style Library** is a good place for the \*.js files, also such as for the style sheets (css). Besides learning JavaScript I would also recommend to have a look at jQuery.
Here are a couple resources you may find useful:

[The SharePoint & jQuery Guide](http://sharepointhillbilly.com/Lists/Posts/Post.aspx?ID=16)

[SharePoint Client-Side Development with the JSOM and jQuery](https://vimeo.com/29124752)