Disadvantages of dynamically including CSS/JS files?

What are the specific disadvantages (if any) of dynamically including the CSS and JS files for a website?

By dynamically, I mean, using the document.write() method generate and tags.

I'd like to use this technique on a very large, high-traffic we开发者_如何学运维bsite, since it allows me to easily manage which files are downloaded for which site sections, and to switch on a compressed mode in which only minified files are downloaded.

Thoughts?

1. Reliability. People may have JS disabled, etc.
2. Debugging. Some browsers (IE) don't give you the included file's line number on an error, but simply the document.write line in the main file.

The advantages are that you can manage and organize your code more easily and you're able to load only those scripts on the page that are absolutely necessary.

The disadvantage, one that I can think of, is that some website performance measuring tools such as PageSpeed and YSlow will warn you about the number of CSS and JavaScript files referenced by a page. Modern web development practices often encourage you to Combine CSS files and Combine JavaScript files to reduce the total number of files required to render a page and improve network performance. Generally speaking, serving one big, bloated file is better than serving 10 small lean-and-mean files because of the overhead associated with requesting a file from the server.