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问题:

I have a page that contains multiple stylesheets and a large majority of the styles in it aren't actually used in the page (deprecated etc). I would like to export a new stylesheet containing all styles on the page that are actually in use. Is there anyway to do this?

回答1:

I think this website does what you want: CSS Trashman. It takes a little while to run, but it works. It reduced my personal site's CSS from 3.31 KB to 402 Bytes.

If you would rather use a command-line tool, CSS Rationator powers CSS Trashman.

回答2:

I had this same issue, complicated by the fact that the pages I need to analyze are login-only, and for work, so I cannot provide my login to an external app (which is how unused-css.com crawls pages behind a login wall).

I found two Chrome extensions:

CSS Remove and Combine
unusedCSS

I only used the first, as it did the trick nicely. It counted CSS elements on the page, told me how many were used and unused, and let me download a stylesheet of all used elements. It did not seem to include functionality for browsing around a site and accumulating seen elements, it was just on a page-by-page basis, but it still let me prune 450 down to 150.

回答3:

In the Chrome DevTools, there is an Audits tab that will allow you to run a Web Page Performance audit and see a list of unused CSS rules :

回答4:

I found this : http://unused-css.com/

Features

Explore the pages of your site automatically, find the unused CSS selectors and create new clean CSS files you can download

Authenticate and explore the pages requiring authentication. It will then check unused CSS rules.

Search for CSS rules in javascript files

Customize the list of CSS selectors to keep

Preview the change made to the CSS file

Follow CSS import commands

Set a user agent for the crawler

But i am not sure this would be a good idea, something like : javascript trigered selectors, contextual display, code conditional layout ... So, be carefull if you attempt to 'batch' work your .css files.