postcss-remove-unused-css

Whitelists CSS selectors based on your other files

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Readme

postcss-remove-unused-css
This is a simple to use PostCSS plugin that removes CSS selectors based on your other files.
This package is inspired by PurifyCSS and works the same.

How it works

It scans your HTML and JS files (you can configure which extensions it looks) and looks for words. Then it compares with words in your CSS selectors and filters out selectors without matches. If you have the word blue written in one of your JS or HTML files, it will allow a selector called .blue in your CSS. It is a simple and imperfect system, but it works.
Unlike UnCSS, the content of your other files don't matter: we're running a simple regex match against the text files instead of a parser. We're also not running any Javascript. Therefore, it is simpler, but it might produce some false-positives. If you need a more precise approach we strongly recommend UnCSS.

Caveats

Don't include CSS files in your extensions. This will make the plugin look for identifiers inside CSS files and the plugin won't optimize your code.
I'm using a simple file traversal algorithm instead of a Glob. I haven't tested it in all operating systems and environments, only the popular ones. Please file an issue and I'll look into it.

Installation:

npm install postcss-remove-unused-css

yarn add postcss-remove-unused-css

Usage

const remover = require('postcss-remove-unused-css');
postcss([remover(options)]);

See PostCSS docs for examples for your environment.

Options

| Name | Type | Description | Default Value | | --------- | -------- | -------------------------- | ---------------------------------------------------------- | | path | String | Path to your project files | "./src" | | exts | Array | Extensions to look into | ".js", ".jsx", ".ts", ".tsx", ".html", ".vue", ".svelte" | | whitelist | Array | Your whitelisted words | "html", "body" |

Using .postcssrc

{
  "plugins": {
    "postcss-remove-unused-css": {
      "path": "./app",
      "exts": [".js", ".html"]
    }
  }
}

Using package.json:

"postcss": {
  "plugins": {
    "postcss-remove-unused-css": {
      "path": "./app",
      "exts": [".js", ".html"]
    }
  }
},

HTML File:

<!DOCTYPE html>
<html>
  <body>
    <div class="blue bold">Hello, world!</div>
  </body>
</html>

Before

body { background: gray }
.blue { color: blue }
.red { color: red }
.pink { color: pink }
.bold { font-weight: bold }
.thin { font-weight: 100 }
.center { text-align: center }

After

body { background: gray }
.blue { color: blue }
.bold { font-weight: bold }

License

Copyright (c) 2019 Silvio Henrique Ferreira. See the LICENSE file for license rights and limitations (MIT).