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Gathering detailed insights and metrics for @csstools/postcss-is-pseudo-class

@csstools/postcss-is-pseudo-class - 5.0.3 | npmpackage.info

@csstools/postcss-is-pseudo-class

PostCSS Tools and Plugins

5.0.3

983

MIT-0

CSS

28.68 kB

5.8

Installations

npm install @csstools/postcss-is-pseudo-class

Developer Guide

BETA

Typescript

Yes

Module System

ESM

Min. Node Version

>=18

Node Version

22.12.0

NPM Version

10.9.0 Pull Requests

Open

3

Total

1,234

Closed

172

Merged

1,059

Issues

Open

6

Total

364

Closed

358

Releases

Unable to fetch releases

Languages

CSS

JavaScript

TypeScript

HTML

Nunjucks

Shell

SCSS

CSS (43.3%)

JavaScript (30.21%)

TypeScript (22.88%)

HTML (3.03%)

Nunjucks (0.48%)

Shell (0.1%)

Developer

csstools

Download Statistics

Total Downloads

Last Day

Last Week

Last Month

Last Year

GitHub Statistics

MIT-0 License

983 Stars

4,382 Commits

77 Forks

9 Watchers

5 Branches

132 Contributors

Updated on Jul 15, 2025

Sponsor this package

https://github.com/sponsors/csstools https://opencollective.com/csstools

Maintainers

View All 132 Contributors

Package Meta Information

Latest Version

5.0.3

Package Id

@csstools/postcss-is-pseudo-class@5.0.3

Unpacked Size

28.68 kB

Size

6.46 kB

File Count

NPM Version

10.9.0

Node Version

22.12.0

Published on

Jun 11, 2025

Total Downloads

Cumulative downloads

Total Downloads

NaN

Last Day

NaN

Compared to previous day

Last Week

NaN

Compared to previous week

Last Month

NaN

Compared to previous month

Last Year

NaN

Compared to previous year

Weekly Downloads

Monthly Downloads

Yearly Downloads

Dependencies

@csstools/selector-specificity postcss-selector-parser

Peer Dependencies

postcss

PostCSS Is Pseudo

PostCSS Is Pseudo Class lets you use the :is pseudo class function, following the CSS Selector specification.

1:is(input, button):is(:hover, :focus) {
2	order: 1;
3}

Becomes :

1input:hover {
2	order: 1;
3}
4input:focus {
5	order: 1;
6}
7button:hover {
8	order: 1;
9}
10button:focus {
11	order: 1;
12}

Usage

Add PostCSS Is Pseudo Class to your project:

1npm install @csstools/postcss-is-pseudo-class --save-dev

Use PostCSS Is Pseudo Class as a PostCSS plugin:

1import postcss from 'postcss';
2import postcssIsPseudoClass from '@csstools/postcss-is-pseudo-class';
3
4postcss([
5  postcssIsPseudoClass(/* pluginOptions */)
6]).process(YOUR_CSS /*, processOptions */);

PostCSS Is Pseudo Class runs in all Node environments, with special instructions for:

Node	Webpack	Gulp	Grunt

Options

preserve

The preserve option determines whether the original notation is preserved. By default, it is not preserved.

1postcss([
2  postcssIsPseudoClass({ preserve: true })
3]).process(YOUR_CSS /*, processOptions */);

1:is(input, button):is(:hover, :focus) {
2	order: 1;
3}

Becomes :

1input:hover {
2	order: 1;
3}
4input:focus {
5	order: 1;
6}
7button:hover {
8	order: 1;
9}
10button:focus {
11	order: 1;
12}
13:is(input, button):is(:hover, :focus) {
14	order: 1;
15}

specificityMatchingName

The specificityMatchingName option allows you to change the selector used to adjust specificity. The default value is does-not-exist. If this is an actual class, id or tag name in your code, you will need to set a different option here.

See how :not is used to modify specificity.

1postcss([
2  postcssIsPseudoClass({ specificityMatchingName: 'something-random' })
3]).process(YOUR_CSS /*, processOptions */);

1:is(.button, button):hover {
2	order: 7;
3}

Becomes :

1.button:hover {
2	order: 7;
3}
4
5button:not(.something-random):hover {
6	order: 7;
7}

onComplexSelector

Warn on complex selectors in :is pseudo class functions.

1postcss([
2  postcssIsPseudoClass({ onComplexSelector: 'warning' })
3]).process(YOUR_CSS /*, processOptions */);

onPseudoElement

Warn when pseudo elements are used in :is pseudo class functions.

⚠️ Pseudo elements are always invalid and will be transformed to ::-csstools-invalid-<pseudo-name>.

1postcss([
2  postcssIsPseudoClass({ onPseudoElement: 'warning' })
3]).process(YOUR_CSS /*, processOptions */);

1:is(::after):hover {
2	order: 1.0;
3}
4
5/* becomes */
6
7::-csstools-invalid-after:hover {
8	order: 1.0;
9}

⚠️ Known shortcomings

Specificity

:is takes the specificity of the most specific list item. We can increase specificity with :not selectors, but we can't decrease it.

Converted selectors are ensured to have the same specificity as :is for the most important bit. Less important bits can have higher specificity that :is.

Before :

specificity: 0, 2, 0

1:is(:hover, :focus):is(.button, button) {
2	order: 7;
3}

After :

1/* specificity: [0, 2, 0] */
2.button:hover {
3	order: 7;
4}
5
6/* specificity: [0, 2, 1] */
7/* last bit is higher than it should be, but middle bit matches */
8button:not(.does-not-exist):hover {
9	order: 7;
10}
11
12/* specificity: [0, 2, 0] */
13.button:focus {
14	order: 7;
15}
16
17/* specificity: [0, 2, 1] */
18/* last bit is higher than it should be, but middle bit matches */
19button:not(.does-not-exist):focus {
20	order: 7;
21}

Complex selectors

Before :

1:is(.alpha > .beta) ~ :is(:focus > .beta) {
2	order: 2;
3}

After :

1.alpha > .beta ~ :focus > .beta {
2	order: 2;
3}

this is a different selector than expected as .beta ~ :focus matches .beta followed by :focus.
avoid these cases.
writing the selector without :is() is advised here

1/* without is */
2.alpha:focus > .beta ~ .beta {
3	order: 2;
4}

If you have a specific pattern you can open an issue to discuss it. We can detect and transform some cases but can't generalize them into a single solution that tackles all of them.

No vulnerabilities found.

10

Maintained

Determines if the project is "actively maintained".

10

Dangerous-Workflow

Determines if the project's GitHub Action workflows avoid dangerous patterns.

10

Security-Policy

Determines if the project has published a security policy.

10

License

Determines if the project has defined a license.

10

Binary-Artifacts

Determines if the project has generated executable (binary) artifacts in the source repository.

9

Vulnerabilities

Determines if the project has open, known unfixed vulnerabilities.

7

SAST

Determines if the project uses static code analysis.

3

Branch-Protection

Determines if the default and release branches are protected with GitHub's branch protection settings.

3

Pinned-Dependencies

Determines if the project has declared and pinned the dependencies of its build process.

Reason

dependency not pinned by hash detected -- score normalized to 3

Details

Warn: GitHub-owned GitHubAction not pinned by hash: .github/workflows/codeql.yml:24: update your workflow using https://app.stepsecurity.io/secureworkflow/csstools/postcss-plugins/codeql.yml/main?enable=pin
Warn: GitHub-owned GitHubAction not pinned by hash: .github/workflows/codeql.yml:27: update your workflow using https://app.stepsecurity.io/secureworkflow/csstools/postcss-plugins/codeql.yml/main?enable=pin
Warn: GitHub-owned GitHubAction not pinned by hash: .github/workflows/codeql.yml:33: update your workflow using https://app.stepsecurity.io/secureworkflow/csstools/postcss-plugins/codeql.yml/main?enable=pin
Warn: GitHub-owned GitHubAction not pinned by hash: .github/workflows/codeql.yml:42: update your workflow using https://app.stepsecurity.io/secureworkflow/csstools/postcss-plugins/codeql.yml/main?enable=pin
Warn: GitHub-owned GitHubAction not pinned by hash: .github/workflows/deploy-preset-env.yml:20: update your workflow using https://app.stepsecurity.io/secureworkflow/csstools/postcss-plugins/deploy-preset-env.yml/main?enable=pin
Warn: GitHub-owned GitHubAction not pinned by hash: .github/workflows/deploy-preset-env.yml:23: update your workflow using https://app.stepsecurity.io/secureworkflow/csstools/postcss-plugins/deploy-preset-env.yml/main?enable=pin
Warn: GitHub-owned GitHubAction not pinned by hash: .github/workflows/labeler.yml:13: update your workflow using https://app.stepsecurity.io/secureworkflow/csstools/postcss-plugins/labeler.yml/main?enable=pin
Warn: GitHub-owned GitHubAction not pinned by hash: .github/workflows/lint.yml:17: update your workflow using https://app.stepsecurity.io/secureworkflow/csstools/postcss-plugins/lint.yml/main?enable=pin
Warn: GitHub-owned GitHubAction not pinned by hash: .github/workflows/lint.yml:20: update your workflow using https://app.stepsecurity.io/secureworkflow/csstools/postcss-plugins/lint.yml/main?enable=pin
Warn: GitHub-owned GitHubAction not pinned by hash: .github/workflows/test.yml:34: update your workflow using https://app.stepsecurity.io/secureworkflow/csstools/postcss-plugins/test.yml/main?enable=pin
Warn: GitHub-owned GitHubAction not pinned by hash: .github/workflows/test.yml:37: update your workflow using https://app.stepsecurity.io/secureworkflow/csstools/postcss-plugins/test.yml/main?enable=pin
Warn: npmCommand not pinned by hash: .github/workflows/test.yml:98
Info: 0 out of 11 GitHub-owned GitHubAction dependencies pinned
Info: 6 out of 7 npmCommand dependencies pinned

0

Code-Review

Determines if the project requires human code review before pull requests (aka merge requests) are merged.

0

CII-Best-Practices

Determines if the project has an OpenSSF (formerly CII) Best Practices Badge.

0

Token-Permissions

Determines if the project's workflows follow the principle of least privilege.

0

Fuzzing

Determines if the project uses fuzzing.

Score

5.8

/10

Last Scanned on 2025-07-07

The Open Source Security Foundation is a cross-industry collaboration to improve the security of open source software (OSS). The Scorecard provides security health metrics for open source projects.

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