Any good ways of combining only necessary css and js for web app

I have been improving the structure开发者_C百科 of a web app's frontend and have done things like combine and minify css/js files, version files, and building out some templates. However I was looking at some web tools and it is saying there is a ton of unused js/css. Are there any suggestions on -discovering the completely necessary code -combining, minifying, and versioning the right code for the page I am mainly looking for like a logical suggestion any code samples would be great. I am specifically using python, cheetah templates, yui-compressor, modified time for versioning, mod_rewrite and gzip on apache

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Check out the Dust-Me Selectors Firefox extension for streamlining CSS:

Dust-Me Selectors is a Firefox extension (for v1.5 or later) that finds unused CSS selectors.

It extracts all the selectors from all the stylesheets on the page you're viewing, then analyzes that page to see which of those selectors are not used. The data is then stored so that when testing subsequent pages, selectors can be crossed off the list as they're encountered.

You can test pages individually, or spider an entire site, and you'll end up with a profile of which selectors are not used anywhere.

For JavaScript, take a look at the Google Closure Compiler which can calculate codependencies within your code and remove redundancies.

The Closure Compiler is a tool for making JavaScript download and run faster. It is a true compiler for JavaScript. Instead of compiling from a source language to machine code, it compiles from JavaScript to better JavaScript. It parses your JavaScript, analyzes it, removes dead code and rewrites and minimizes what's left. It also checks syntax, variable references, and types, and warns about common JavaScript pitfalls.