CODEWITHSUNDEEP
css
user658182
user658182

Reputation: 2350

How can I extract only the used CSS on a given web page and have that combined into a separate style sheet?

I have a site whose stylesheets are becoming overwhelming, and a full 50% to 90% or so is not used on certain pages. Rather than have 23 separate blocking CSS sheets, I'd like to find out which are being used on the page I'd like to target, and have those exported into one sheet.

I have seen several questions that recommend "Dust me selectors" or similar add on which will tell what selectors are and are not being used; but that's not what I want. I need to be able to export all used styles from all sheets for that particular page into one new sheet that can be used to replace the 23 others. The solution should be able to support a responsive website (media calls). The website page I'm targeting is: http://tripinary.com.

I've found: https://unused-css.com but this is a paid service and I need free;

The next closest thing I've come across is http://www.csstrashman.com/ but this does not look at stylesheets. In fact, it completely ignores them and ultimately I'm having trouble with the responsiveness of the site. Many times as well, this site just crashes.

I don't mind a programmatic solution if someone has had to do this before and can recommend a direction.

Upvotes: 22

Views: 19300

Answers (6)

Shashwat Sahai
Shashwat Sahai

Reputation: 11

Try using this tool,which is just a simple js script https://github.com/shashwatsahai/CSSExtractor/ This tool helps in getting the CSS from a specific page listing all sources for active styles and save it to a JSON with source as key and rules as value. It loads all the CSS from the href links and tells all the styles applied from them You can modify the code to save all css into a .css file. Thereby combining all your css.

Upvotes: 0

Ari Porad
Ari Porad

Reputation: 2922

If you wanted, you could try to build a script that runs on a (non-production) server that goes through every css rule, removes it from the stylesheet, loads the page using something like phantomjs, and checks to see if anything changed from the last time it loaded the page. If so, then put the css rule back, if not, then leave it out and move on to the next rule. It would take a while to run, but it would work. You would also have to setup an instance of your server that does not use caching for it to run on.

Upvotes: 1

Mayank Bothra
Mayank Bothra

Reputation: 93

You Can Check in Google Chrome by doing inspect element (F12) . The unused CSS has Line over the tags.

Upvotes: 1

FelipeAls
FelipeAls

Reputation: 22161

(deleted my comment to RwwL answer to make it a thorough answer)

UnCSS, whether node.js or as a grunt or gulp task, is able to list used CSS rules by an array of pages in an array of Media Queries.

uncss: https://github.com/giakki/uncss
grunt-uncss: https://github.com/addyosmani/grunt-uncss
gulp-uncss: https://github.com/ben-eb/gulp-uncss

Multipage:

You can pass files as an argument to any of the 3 plugins, like:

var files   = ['my', 'array', 'of', 'HTML', 'files'],
    options = { /* (…) */ };

uncss(files, options, function (error, output) {
    console.log(output);
});

Avoid:

urls (Array):
array of URLs to load with Phantom (on top of the files already passed if any).
NOTE: this feature is deprecated, you can pass URLs directly as arguments.

 
Media Queries and responsive are taken into account:

media (Array):
By default UnCSS processes only stylesheets with media query "all", "screen", and those without one. Specify here which others to include.

You can add stylesheets, ignore some of them, add inline CSS and many other options like htmlroot

 
Remaining problems:

1/ Conditional classes if you use them for IE9-. They obviously won't be matched in a WebKit PhantomJS environment! 

HTML:
<!--[if IE 9]><html class="ie9 lte-ie9" lang="en"><![endif]--> <!-- teh conditional comment/class -->

CSS:
.ie9 .some-class { property: value; ] /* Only matched in IE9, not WebKit PhantomJS */

Should they be added by hand or script to the html element in testing environment? (how it renders is of no importance)
Is there an option in uncss?
As long as you don't style with :not(.ie9) (weird), it should be fine.

EDIT: you can use the ignore option with a pattern to force uncss to "provide a list of selectors that should not be removed by UnCSS". Won't be tested though.

2/ Scripts that will detect resolution (viewport width) and adapt content to it by removing/adding it or adding a class on a container. They will execute in PhantomJS in desktop resolution I guess and thus won't do their job so you'll need to modify calls to PhantomJS or something like that... Or dig into options or GitHub issues of the 3 projects (I didn't)

Other tools I heard of, not tested or barely or couldn't test, no idea about the MQ part:

  • in grunt-uncss readme, the Coverage part
  • ucss from Opera (there's already an ansswer here, couldn't make it work)
  • Helium
  • CSSESS
  • mincss

Addy Osmani has countless presentations of 100+ slides presenting awesome tools like this one: https://speakerdeck.com/addyosmani/automating-front-end-workflow (you'll regret even more that days are made only of 24 hours and not 48 err wait 72 ^^)

Upvotes: 17

bishop
bishop

Reputation: 39354

How about the CSS Usage plugin for Firebug?

Steps:

  1. Visit your page in Firefox
  2. Click "CSS Usage" tab in Firebug
  3. Click the Scan button
  4. Click the bold file name
  5. Save page of CSS selectors to disk

Here are some screen shots and walk through. Not sure about media queries or if it'll work on your site, and it'll probably not keep -webkit etc, but maybe it'll get you part of the way there.

Upvotes: 7

RwwL
RwwL

Reputation: 3308

Opera Software released a CSS crawler on Github that claims it can find unused and duplicate selectors. It might do the trick if you're comfortable with a command-line tool. https://github.com/operasoftware/ucss

Upvotes: 2

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