CSS validator built on csstree
npm install csstree-validator
CSS Validator built on CSSTree.
Technically, the package utilizes the capabilities of CSSTree to match CSS syntaxes to various parts of your code and generates a list of errors, if any.
> Note: If csstree-validator produces false positives or false negatives, such as unknown properties or invalid values for a property, please report the issue to the CSSTree issue tracker.
> Note: CSSTree currently doesn't support selector syntax matching; therefore, csstree-validator doesn't support it either. Support for selector validation will be added once it is available in CSSTree.
Install the package via npm:
``bash`
npm install csstree-validator
You can validate a CSS string or a CSSTree AST:
`js
import { validate } from 'csstree-validator';
// For CommonJS:
// const { validate } = require('csstree-validator');
const filename = 'demo/example.css';
const css = '.class { pading: 10px; border: 1px super red }';
console.log(validate(css, filename));
// Output:
// [
// SyntaxError [SyntaxReferenceError]: Unknown property pading {border
// reference: 'pading',
// property: 'pading',
// offset: 9,
// line: 1,
// column: 10
// },
// SyntaxError [SyntaxMatchError]: Mismatch {
// message: 'Invalid value for property',`
// rawMessage: 'Mismatch',
// syntax: '
// css: '1px super red',
// mismatchOffset: 4,
// mismatchLength: 5,
// offset: 35,
// line: 1,
// column: 36,
// loc: { source: 'demo/example.css', start: [Object], end: [Object] },
// property: 'border',
// details: 'Mismatch\n' +
// ' syntax:
// ' value: 1px super red\n' +
// ' ------------^'
// }
// ]
Alternatively, you can use helper functions to validate a file or directory and utilize one of the built-in reporters:
`js
import { validateFile, reporters } from 'csstree-validator';
const result = validateFile('./path/to/style.css');
console.log(reporters.checkstyle(result));
`
- validate(css, filename)
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> Note: Helpers are not available in browser environments as they rely on Node.js APIs.
All helper functions return an object where the key is the path to a file and the value is an array of errors. The result object is iterable (has Symbol.iterator) and can be used with for...of loops or the spread operator.
Example:
`js
const result = validateFile('path/to/file.css');
for (const [filename, errors] of result) {
// Process errors
}
`
Available helper functions:
- validateString(css, filename)
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CSSTree Validator provides several built-in reporters to convert validation results into different formats:
- console – Human-readable text suitable for console output.json
- – Converts errors into a unified JSON array of objects:
`ts`
type ErrorEntry = {
name: string; // Filename
line: number;
column: number;
atrule?: string;
descriptor?: string;
property?: string;
message: string;
details?: any;
}
- checkstyle – Checkstyle XML report format:
`xml`
- gnu – GNU error log format:
`
"FILENAME":LINE.COLUMN: error: MESSAGE
"FILENAME":START_LINE.COLUMN-END_LINE.COLUMN: error: MESSAGE
Example usage:
`js
import { validate, reporters } from 'csstree-validator';
const css = '.class { padding: 10px; color: red; }';
const result = validate(css, 'example.css');
console.log(reporters.json(result));
// Output:
// [
// { "name": 'example.css', ... },
// { "name": 'example.css', ... },
// ...
// ]
`
CSSTree Validator can be used in browser environments using the available bundles:
- IIFE Bundle (dist/csstree-validator.js) – Minified IIFE with csstreeValidator as a global variable.
`html`
- ES Module (dist/csstree-validator.esm.js) – Minified ES module.
`html`
You can also use a CDN service like unpkg or jsDelivr. By default, the ESM version is exposed for short paths. For the IIFE version, specify the full path to the bundle:
`html
`
Note: Helpers are not available in the browser version.
Install globally via npm:
`bash`
npm install -g csstree-validator
Run the validator on a CSS file:
`bash`
csstree-validator /path/to/style.css
Display help:
`bash`
csstree-validator -h
`
Usage:
csstree-validator [fileOrDir] [options]
Options:
-h, --help Output usage information
-r, --reporter
or
-v, --version Output version
`
In addition to the built-in reporters, you can specify a custom reporter by providing the path to a module or package. The module should export a single function that takes the validation result object and returns a string:
`js
export default function(result) {
let output = '';
for (const [filename, errors] of result) {
// Generate custom output
}
return output;
}
// For CommonJS:
// module.exports = function(result) { ... }
`
The reporter option accepts:
- ESM Module – Full path to a file with a .js extension..cjs
- CommonJS Module – Full path to a file with a extension.
- ESM Package – Package name or full path to a module within the package.
- CommonJS Package – Package name or path to a module within the package.
- Dual Package – Package name or full path to a module within the package.
The resolution algorithm checks the reporter value in the following order:
1. If it's a path to a file (relative to process.cwd()), use it as a module.process.cwd()
2. If it's a path to a package module (relative to ), use the package's module.
3. Otherwise, the value should be the name of one of the predefined reporters, or an error will be raised.
Plugins that use csstree-validator`:
MIT