importsToResolve.js
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"use strict";
const path = require("path");
const utils = require("loader-utils");
const matchModuleImport = /^~([^\/]+|@[^\/]+[\/][^\/]+)$/;
/**
* When libsass tries to resolve an import, it uses a special algorithm.
* Since the sass-loader uses webpack to resolve the modules, we need to simulate that algorithm. This function
* returns an array of import paths to try. The last entry in the array is always the original url
* to enable straight-forward webpack.config aliases.
*
* @param {string} url
* @returns {Array<string>}
*/
function importsToResolve(url) {
const request = utils.urlToRequest(url);
// Keep in mind: ext can also be something like '.datepicker' when the true extension is omitted and the filename contains a dot.
// @see https://github.com/webpack-contrib/sass-loader/issues/167
const ext = path.extname(request);
if (matchModuleImport.test(url)) {
return [request, url];
}
// libsass' import algorithm works like this:
// In case there is a file extension...
// - If the file is a CSS-file, do not include it all, but just link it via @import url().
// - The exact file name must match (no auto-resolving of '_'-modules).
if (ext === ".css") {
return [];
}
if (ext === ".scss" || ext === ".sass") {
return [request, url];
}
// In case there is no file extension...
// - Prefer modules starting with '_'.
// - File extension precedence: .scss, .sass, .css.
const basename = path.basename(request);
if (basename.charAt(0) === "_") {
return [
`${ request }.scss`, `${ request }.sass`, `${ request }.css`,
url
];
}
const dirname = path.dirname(request);
return [
`${ dirname }/_${ basename }.scss`, `${ dirname }/_${ basename }.sass`, `${ dirname }/_${ basename }.css`,
`${ request }.scss`, `${ request }.sass`, `${ request }.css`,
url
];
}
module.exports = importsToResolve;