stylelint/lib/utils/isStandardSyntaxDeclaration.js

A mighty, modern CSS linter.

/* @flow */
'use strict';

function isStandardSyntaxLang(lang) {
	return lang && (lang === 'css' || lang === 'custom-template' || lang === 'template-literal');
}

/**
 * Check whether a declaration is standard
 */
module.exports = function(decl /*: Object*/) /*: boolean*/ {
	const prop = decl.prop;
	const parent = decl.parent;

	// Declarations belong in a declaration block or standard CSS source
	if (parent.type === 'root' && !isStandardSyntaxLang(parent.source.lang)) {
		return false;
	}

	// Sass var (e.g. $var: x), nested list (e.g. $list: (x)) or nested map (e.g. $map: (key:value))
	if (prop[0] === '$') {
		return false;
	}

	// Less var (e.g. @var: x), but exclude variable interpolation (e.g. @{var})
	if (prop[0] === '@' && prop[1] !== '{') {
		return false;
	}

	// Sass nested properties (e.g. border: { style: solid; color: red; })
	if (
		parent.selector &&
		parent.selector[parent.selector.length - 1] === ':' &&
		parent.selector.substring(0, 2) !== '--'
	) {
		return false;
	}

	// Less &:extend
	if (decl.extend) {
		return false;
	}

	return true;
};