Registry / serialization / hast-util-is-css-style

hast-util-is-css-style

library3.0.1jsnpmunverified

hast-util-is-css-style is a focused utility from the unified ecosystem, specifically designed to inspect HAST (HTML Abstract Syntax Tree) nodes. Its primary function is to determine whether a given HAST node represents an HTML <style> element that is intended to contain CSS. This utility is currently stable at version 3.0.1 and is part of a larger monorepo (rehypejs/rehype-minify) which tends to release updates synchronously across related packages, especially for major ecosystem changes (e.g., Node.js version support, ESM-only shifts). Its key differentiator lies in its deep integration with the hast specification, ensuring accurate identification of CSS style elements based on their type attribute, including default cases and various text/css variations, which is crucial for tools that parse, transform, or optimize HTML content.

serialization web-framework

npm install hast-util-is-css-style

github ↗package ↗

INSTALL

IMPORT

SIG · HAST-UTIL-IS-CSS-S

hast-util-is-css-style

serializationjavascriptv3.0.1

Install

—

Import

—

Disk

—

Pass rate

0/ 6

Env Coverage0 / 6

glibc

18–22

musl

18–22

Install & Compatibility

Where this runs

tested against v? · npm install

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

node 18–226 runs

build_error

glibc

node 18–226 runs

build_error

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

isCssStyle

✓ import {isCssStyle} from 'hast-util-is-css-style'

✗ const {isCssStyle} = require('hast-util-is-css-style')

This package is ESM-only since version 3. CommonJS `require()` is not supported.

Node

✓ import type {Node} from 'hast'

While `isCssStyle` operates on `Node` from `unist` directly, `hast` provides a more specific type definition for HTML AST nodes which is commonly used in this ecosystem.

✓ import {h} from 'hastscript'

✗ import h from 'hastscript'

Used for creating HAST nodes in examples and tests; `hastscript` uses named exports.

This example demonstrates how to use `isCssStyle` to identify HTML `<style>` elements containing CSS, handling various `type` attribute scenarios and non-style elements.

import {h} from 'hastscript'; import {isCssStyle} from 'hast-util-is-css-style'; // Create various HAST nodes to test const styleNodeWithoutType = h('style', 'body { color: red; }'); const styleNodeWithCssType = h('style', {type: 'text/css'}, 'p { font-size: 16px; }'); const styleNodeWithMixedCaseCssType = h('style', {type: ' TEXT/CSS '}, 'a { text-decoration: none; }'); const styleNodeWithNonCssType = h('style', {type: 'text/foo'}, '.foo { display: block; }'); const scriptNode = h('script', 'console.log("hello");'); const divNode = h('div', 'Some content'); // Check if each node is considered a CSS style element console.log('Is <style> (no type) CSS style?', isCssStyle(styleNodeWithoutType)); // Expected: true console.log('Is <style type="text/css"> CSS style?', isCssStyle(styleNodeWithCssType)); // Expected: true console.log('Is <style type=" TEXT/CSS "> CSS style?', isCssStyle(styleNodeWithMixedCaseCssType)); // Expected: true console.log('Is <style type="text/foo"> CSS style?', isCssStyle(styleNodeWithNonCssType)); // Expected: false console.log('Is <script> CSS style?', isCssStyle(scriptNode)); // Expected: false console.log('Is <div> CSS style?', isCssStyle(divNode)); // Expected: false

Debug

Known issues

breakingVersion 3 of `hast-util-is-css-style` is an ECMAScript Module (ESM) only package. Attempting to `require()` it in CommonJS environments will result in an error.

fix

Ensure your project is configured for ESM, or use dynamic `import()` if you must load it from a CommonJS module. Upgrade to Node.js 16+.

affects: >=3.0.0

breakingThis package, and the broader `unified` ecosystem, requires Node.js version 16 or newer for compatibility. Older Node.js versions are not supported.

fix

Upgrade your Node.js runtime to version 16 or higher.

affects: >=3.0.0

breakingDue to the adoption of the `exports` field in `package.json` across the `rehypejs` monorepo (e.g., in `7.0.0` for related packages), direct imports to internal paths (e.g., `hast-util-is-css-style/lib/foo.js`) are no longer supported. Only documented public APIs should be imported.

fix

Only use public import paths like `hast-util-is-css-style` for module imports.

affects: >=3.0.0

gotchaWorking with HAST and HTML can introduce security vulnerabilities, specifically Cross-Site Scripting (XSS), if not handled carefully. `hast-util-is-css-style` itself is a utility for inspection and does not inherently mitigate these risks.

fix

When processing untrusted HTML, always use a sanitizer like `rehype-sanitize` in your processing pipeline to ensure the generated output is safe.

affects: *

Errors

Common errors & fixes

ERR_REQUIRE_ESM

Attempting to import `hast-util-is-css-style` using CommonJS `require()` in a Node.js environment where it is exclusively an ESM package.

fix

Change `const {isCssStyle} = require('hast-util-is-css-style')` to `import {isCssStyle} from 'hast-util-is-css-style'` and ensure your Node.js environment supports ESM (e.g., by using `"type": "module"` in `package.json` or by using `.mjs` file extensions).

TypeError: isCssStyle is not a function

This typically happens in a CommonJS context when `require()` is used on an ESM-only package that exports named exports, or when `require()` is used on a mixed module that's interpreted incorrectly.

fix

As `hast-util-is-css-style` is ESM-only, ensure you are using `import {isCssStyle} from 'hast-util-is-css-style'` within an ESM context.

ReferenceError: require is not defined

You are trying to use `require` in an ESM module context (e.g., in a file with `"type": "module"` or `.mjs` extension) where `require` is not globally available.

fix

Refactor your code to use `import` statements instead of `require` for all module dependencies. If you need to load CommonJS modules from ESM, consider `import pkg from 'some-cjs-package';` or `const cjsModule = await import('some-cjs-package');`.

Upgrade

Version history

3.0.1latest on npm

Audit

Dependencies

No dependency data recorded yet.

Agent activity

4 hits · last 30 days

node

Resources

githubhttps://github.com/rehypejs/rehype-minify.git#main ↗

packagehttps://www.npmjs.com/package/hast-util-is-css-style ↗