postcss-html

What is postcss-html?

The postcss-html npm package is a tool that allows PostCSS to be used with HTML, including HTML-like syntaxes such as XML, XHTML, and HTML with inline styles. It enables developers to process styles within `<style>` tags or inline `style` attributes using PostCSS plugins.

What are postcss-html's main functionalities?

Processing inline styles

This feature allows processing of inline styles within HTML. The code sample demonstrates how to use postcss-html to process a string containing HTML with a `<style>` tag.

const postcssHtml = require('postcss-html');
const result = postcssHtml.process('<style>h1 { color: red; }</style>', { /* options */ }).then(result => {
  console.log(result.html);
});

Processing styles in HTML-like files

This feature processes styles within HTML-like files. The code sample shows how to read an HTML file, process it with postcss-html, and then write the processed HTML to a new file.

const postcssHtml = require('postcss-html');
const fs = require('fs');

fs.readFile('index.html', (err, html) => {
  if (err) throw err;
  postcssHtml.process(html, { /* options */ }).then(result => {
    fs.writeFile('index-processed.html', result.html, (err) => {
      if (err) throw err;
      console.log('The file has been saved!');
    });
  });
});

Other packages similar to postcss-html

postcss-scss

The postcss-scss package is a syntax for PostCSS that allows you to work with SCSS (Sassy CSS) directly, without converting it to CSS first. It is similar to postcss-html in that it extends PostCSS's capabilities to non-standard CSS syntaxes, but it focuses on SCSS rather than HTML.

postcss-jsx

postcss-jsx is an npm package that enables PostCSS to parse and transform CSS within JSX files. It is similar to postcss-html as it extends PostCSS to handle CSS within a different context (JSX instead of HTML), allowing for linting and other transformations within JavaScript frameworks like React.

stylelint

stylelint is a powerful, modern linter that helps you avoid errors and enforce conventions in your styles. It is similar to postcss-html in that it can be used to lint styles within HTML files, but it is primarily a standalone tool rather than a PostCSS plugin.

README

PostCSS HTML Syntax

PostCSS syntax for parsing HTML (and HTML-like)

• Vue Single-File Components
• Svelte Components
• Astro Components
• PHP
• Quick App
• XSLT

Getting Started

First thing's first, install the module:

npm install postcss-html --save-dev

If you want support SCSS/SASS/LESS/SugarSS syntax, you need to install the corresponding module.

• SCSS: postcss-scss
• SASS: postcss-sass
• LESS: postcss-less
• SugarSS: sugarss
• Stylus: postcss-styl

Use Cases

const postcss = require('postcss');
const syntax = require('postcss-html')({
    // syntax for parse scss (non-required options)
    scss: require('postcss-scss'),
    // syntax for parse less (non-required options)
    less: require('postcss-less'),
    // syntax for parse css blocks (non-required options)
    css: require('postcss-safe-parser'),
});
postcss(plugins).process(source, { syntax: syntax }).then(function (result) {
    // An alias for the result.css property. Use it with syntaxes that generate non-CSS output.
    result.content
});

If you want support SCSS/SASS/LESS/SugarSS syntax, you need to install these module:

• SCSS: postcss-scss
• SASS: postcss-sass
• LESS: postcss-less
• SugarSS: sugarss
• Stylus: postcss-styl

Advanced Use Cases

Options

const options = {
    rules: [
        {
            // custom language
            test: /^postcss$/i,
            lang: 'scss'
        },
        {
            // custom language
            test: /^customcss$/i,
            lang: 'custom'
        },
    ],

    // custom parser for CSS (using `postcss-safe-parser`)
    css: 'postcss-safe-parser',
    // custom parser for SASS (PostCSS-compatible syntax.)
    sass: require('postcss-sass'),
    // custom parser for SCSS (by module name)
    scss: 'postcss-scss',
    // custom parser for LESS (by module path)
    less: require.resolve('./node_modules/postcss-less'),
    // custom parser for SugarSS
    sugarss: require('sugarss'),
    // custom parser for custom language
    custom: require('postcss-custom-syntax'),
}
const syntax = require('postcss-html')(options);

Turning PostCSS off from within your HTML

PostCSS can be temporarily turned off by using special comments in your HTML. For example:

<html>
<body>
<!-- postcss-ignore -->
<a style="color: red;" description="style is not parsed."></a>

<a style="color: red;" description="style is parsed."></a>

<html>
<body>
<!-- postcss-disable -->
<a style="color: red;" description="style is not parsed."></a>
<a style="color: red;" description="style is not parsed."></a>
<!-- postcss-enable -->

<a style="color: red;" description="style is parsed."></a>

Linting with Stylelint

The main use case of this plugin is to apply linting with Stylelint to <style> tags and <div style="*"> property in HTML (and HTML-like).

You can use it by configuring your stylelint config as follows:

{
    "overrides": [
        {
            "files": ["*.html", "**/*.html"],
            "customSyntax": "postcss-html"
        }
    ]
}

You can use it more easily if you use an already configured sharable config.

{
+    "extends": [
+        "stylelint-config-html",
         // If you are using Vue.
+        "stylelint-config-recommended-vue"
+    ],
-    "overrides": [
-        {
-            "files": ["*.html", "**/*.html"],
-            "customSyntax": "postcss-html"
-        }
-    ]
}

• stylelint-config-html
• stylelint-config-recommended-vue