Sample code for Vue build utils

utils.js

function cssLoaders(options = {}) {
    const defaultLoaderOptions = !_.has(options, 'sourceMap') ? false : { sourceMap: options.sourceMap };

    const cssLoader = {
        loader: 'css-loader',
        options: {
            sourceMap: options.sourceMap,
            minimize: nodeEnv === 'production'
        }
    };

    /**
     * Generate css loaders for given loader
     *
     * @param {string|Object} loader
     * @return {Array|Object} Array of loaders to be used or the Extract text loader
     */
    function generateLoaders(loader) {
        const styleLoaders = [cssLoader];
        if (loader) {
            let styleLoader;
            if (_.isString(loader)) {
                styleLoader = defaultLoaderOptions === false ? `${loader}-loader` : {
                    loader: `${loader}-loader`,
                    options: defaultLoaderOptions
                };
            } else { // assume it is an object
                if (defaultLoaderOptions !== false) {
                    _.assign(loader.options, defaultLoaderOptions);
                }
                styleLoader = loader;
            }
            styleLoaders.push(styleLoader); // loadeObj can be string/object
        }

        // Extract CSS when that option is specified
        // (which is the case during production build)
        if (options.extract) {
            return ExtractTextPlugin.extract({
                use: styleLoaders,
                fallback: 'vue-style-loader'
            });
        }
        return ['vue-style-loader', ...styleLoaders];
    }

    // http://vuejs.github.io/vue-loader/en/configurations/extract-css.html
    return {
        css: generateLoaders(),
        postcss: generateLoaders(),
        less: generateLoaders('less'),
        sass: generateLoaders({ loader: 'sass-loader', options: { indentedSyntax: true } }),
        scss: generateLoaders('sass'),
        stylus: generateLoaders('stylus'),
        styl: generateLoaders('stylus')
    };
};