React JS Webpack failure for Node SASS - node.js

Question

below code is my webpack.config.dev.js.
I got the webpack config after running npm run eject as you might already know.
I installed node-sass and sass-loader packages.
I included the webpack build configuration.
When I run npm start I get invalid schema error. If I try to fix this I get
module export error for bootstrap 4 module that I had already included in the project.
webpack.config.dev.js
const path = require('path');
const webpack = require('webpack');
const PnpWebpackPlugin = require('pnp-webpack-plugin');
const HtmlWebpackPlugin = require('html-webpack-plugin');
const CaseSensitivePathsPlugin = require('case-sensitive-paths-webpack-plugin');
const InterpolateHtmlPlugin = require('react-dev-utils/InterpolateHtmlPlugin');
const WatchMissingNodeModulesPlugin = require('react-dev-utils/WatchMissingNodeModulesPlugin');
const ModuleScopePlugin = require('react-dev-utils/ModuleScopePlugin');
const getCSSModuleLocalIdent = require('react-dev-utils/getCSSModuleLocalIdent');
const ManifestPlugin = require('webpack-manifest-plugin');
const getCacheIdentifier = require('react-dev-utils/getCacheIdentifier');
const ModuleNotFoundPlugin = require('react-dev-utils/ModuleNotFoundPlugin');
const getClientEnvironment = require('./env');
const paths = require('./paths');
// Webpack uses `publicPath` to determine where the app is being served from.
// In development, we always serve from the root. This makes config easier.
const publicPath = '/';
// `publicUrl` is just like `publicPath`, but we will provide it to our app
// as %PUBLIC_URL% in `index.html` and `process.env.PUBLIC_URL` in JavaScript.
// Omit trailing slash as %PUBLIC_PATH%/xyz looks better than %PUBLIC_PATH%xyz.
const publicUrl = '';
// Get environment variables to inject into our app.
const env = getClientEnvironment(publicUrl);
// style files regexes
const cssRegex = /\.css$/;
const cssModuleRegex = /\.module\.css$/;
const sassRegex = /\.(scss|sass)$/;
const sassModuleRegex = /\.module\.(scss|sass)$/;
// common function to get style loaders
const getStyleLoaders = (cssOptions, preProcessor) => {
const loaders = [
require.resolve('style-loader'),
{
loader: require.resolve('css-loader'),
options: cssOptions,
},
{
// Options for PostCSS as we reference these options twice
// Adds vendor prefixing based on your specified browser support in
// package.json
loader: require.resolve('postcss-loader'),
options: {
// Necessary for external CSS imports to work
// https://github.com/facebook/create-react-app/issues/2677
ident: 'postcss',
plugins: () => [
require('postcss-flexbugs-fixes'),
require('postcss-preset-env')({
autoprefixer: {
flexbox: 'no-2009',
},
stage: 3,
}),
],
},
},
// ------------------------ Add SCSS Loaders --------------------------------
// ------------------------ This where I am getting issue ------------ Help needed here
{
test: /\.scss$/,
loaders: [
require.resolve('style-loader'),
require.resolve('css-loader'),
require.resolve('sass-loader')
],
},
{
exclude: [/\.(js|jsx|mjs)$/, /\.html$/, /\.json$/, /\.scss$/],
loader: require.resolve('file-loader'),
options: {
name: 'static/media/[name].[hash:8].[ext]',
},
}
];
if (preProcessor) {
loaders.push(require.resolve(preProcessor));
}
return loaders;
};
// This is the development configuration.
// It is focused on developer experience and fast rebuilds.
// The production configuration is different and lives in a separate file.
module.exports = {
mode: 'development',
// You may want 'eval' instead if you prefer to see the compiled output in DevTools.
// See the discussion in https://github.com/facebook/create-react-app/issues/343
devtool: 'cheap-module-source-map',
// These are the "entry points" to our application.
// This means they will be the "root" imports that are included in JS bundle.
entry: [
// Include an alternative client for WebpackDevServer. A client's job is to
// connect to WebpackDevServer by a socket and get notified about changes.
// When you save a file, the client will either apply hot updates (in case
// of CSS changes), or refresh the page (in case of JS changes). When you
// make a syntax error, this client will display a syntax error overlay.
// Note: instead of the default WebpackDevServer client, we use a custom one
// to bring better experience for Create React App users. You can replace
// the line below with these two lines if you prefer the stock client:
// require.resolve('webpack-dev-server/client') + '?/',
// require.resolve('webpack/hot/dev-server'),
require.resolve('react-dev-utils/webpackHotDevClient'),
// Finally, this is your app's code:
paths.appIndexJs,
// We include the app code last so that if there is a runtime error during
// initialization, it doesn't blow up the WebpackDevServer client, and
// changing JS code would still trigger a refresh.
],
output: {
// Add /* filename */ comments to generated require()s in the output.
pathinfo: true,
// This does not produce a real file. It's just the virtual path that is
// served by WebpackDevServer in development. This is the JS bundle
// containing code from all our entry points, and the Webpack runtime.
filename: 'static/js/bundle.js',
// There are also additional JS chunk files if you use code splitting.
chunkFilename: 'static/js/[name].chunk.js',
// This is the URL that app is served from. We use "/" in development.
publicPath,
// Point sourcemap entries to original disk location (format as URL on Windows)
devtoolModuleFilenameTemplate: info => path.resolve(info.absoluteResourcePath).replace(/\\/g, '/'),
},
optimization: {
// Automatically split vendor and commons
// https://twitter.com/wSokra/status/969633336732905474
// https://medium.com/webpack/webpack-4-code-splitting-chunk-graph-and-the-splitchunks-optimization-be739a861366
splitChunks: {
chunks: 'all',
name: false,
},
// Keep the runtime chunk seperated to enable long term caching
// https://twitter.com/wSokra/status/969679223278505985
runtimeChunk: true,
},
resolve: {
// This allows you to set a fallback for where Webpack should look for modules.
// We placed these paths second because we want `node_modules` to "win"
// if there are any conflicts. This matches Node resolution mechanism.
// https://github.com/facebook/create-react-app/issues/253
modules: ['node_modules'].concat(
// It is guaranteed to exist because we tweak it in `env.js`
process.env.NODE_PATH.split(path.delimiter).filter(Boolean)
),
// These are the reasonable defaults supported by the Node ecosystem.
// We also include JSX as a common component filename extension to support
// some tools, although we do not recommend using it, see:
// https://github.com/facebook/create-react-app/issues/290
// `web` extension prefixes have been added for better support
// for React Native Web.
extensions: ['.web.js', '.js', '.json', '.web.jsx', '.jsx'],
alias: {
// Support React Native Web
// https://www.smashingmagazine.com/2016/08/a-glimpse-into-the-future-with-react-native-for-web/
'react-native': 'react-native-web',
},
plugins: [
// Adds support for installing with Plug'n'Play, leading to faster installs and adding
// guards against forgotten dependencies and such.
PnpWebpackPlugin,
// Prevents users from importing files from outside of src/ (or node_modules/).
// This often causes confusion because we only process files within src/ with babel.
// To fix this, we prevent you from importing files out of src/ -- if you'd like to,
// please link the files into your node_modules/ and let module-resolution kick in.
// Make sure your source files are compiled, as they will not be processed in any way.
new ModuleScopePlugin(paths.appSrc, [paths.appPackageJson]),
],
},
resolveLoader: {
plugins: [
// Also related to Plug'n'Play, but this time it tells Webpack to load its loaders
// from the current package.
PnpWebpackPlugin.moduleLoader(module),
],
},
module: {
strictExportPresence: true,
rules: [
// Disable require.ensure as it's not a standard language feature.
{ parser: { requireEnsure: false } },
// First, run the linter.
// It's important to do this before Babel processes the JS.
{
test: /\.(js|jsx)$/,
enforce: 'pre',
use: [
{
options: {
formatter: require.resolve('react-dev-utils/eslintFormatter'),
eslintPath: require.resolve('eslint'),
},
loader: require.resolve('eslint-loader'),
},
],
include: paths.appSrc,
},
{
// `mjs` support is still in its infancy in the ecosystem, so we don't
// support it.
// Modules who define their `browser` or `module` key as `mjs` force
// the use of this extension, so we need to tell webpack to fall back
// to auto mode (ES Module interop, allows ESM to import CommonJS).
test: /\.mjs$/,
include: /node_modules/,
type: 'javascript/auto',
},
{
// "oneOf" will traverse all following loaders until one will
// match the requirements. When no loader matches it will fall
// back to the "file" loader at the end of the loader list.
oneOf: [
// "url" loader works like "file" loader except that it embeds assets
// smaller than specified limit in bytes as data URLs to avoid requests.
// A missing `test` is equivalent to a match.
{
test: [/\.bmp$/, /\.gif$/, /\.jpe?g$/, /\.png$/],
loader: require.resolve('url-loader'),
options: {
limit: 10000,
name: 'static/media/[name].[hash:8].[ext]',
},
},
// Process application JS with Babel.
// The preset includes JSX, Flow, and some ESnext features.
{
test: /\.(js|jsx)$/,
include: paths.appSrc,
loader: require.resolve('babel-loader'),
options: {
customize: require.resolve(
'babel-preset-react-app/webpack-overrides'
),
plugins: [
[
require.resolve('babel-plugin-named-asset-import'),
{
loaderMap: {
svg: {
ReactComponent: '#svgr/webpack?-prettier,-svgo![path]',
},
},
},
],
],
// This is a feature of `babel-loader` for webpack (not Babel itself).
// It enables caching results in ./node_modules/.cache/babel-loader/
// directory for faster rebuilds.
cacheDirectory: true,
// Don't waste time on Gzipping the cache
cacheCompression: false,
},
},
// Process any JS outside of the app with Babel.
// Unlike the application JS, we only compile the standard ES features.
{
test: /\.js$/,
exclude: /#babel(?:\/|\\{1,2})runtime/,
loader: require.resolve('babel-loader'),
options: {
babelrc: false,
configFile: false,
compact: false,
presets: [
[
require.resolve('babel-preset-react-app/dependencies'),
{ helpers: true },
],
],
cacheDirectory: true,
// Don't waste time on Gzipping the cache
cacheCompression: false,
// If an error happens in a package, it's possible to be
// because it was compiled. Thus, we don't want the browser
// debugger to show the original code. Instead, the code
// being evaluated would be much more helpful.
sourceMaps: false,
},
},
// "postcss" loader applies autoprefixer to our CSS.
// "css" loader resolves paths in CSS and adds assets as dependencies.
// "style" loader turns CSS into JS modules that inject <style> tags.
// In production, we use a plugin to extract that CSS to a file, but
// in development "style" loader enables hot editing of CSS.
// By default we support CSS Modules with the extension .module.css
{
test: cssRegex,
exclude: cssModuleRegex,
use: getStyleLoaders({
importLoaders: 1,
}),
},
// Adds support for CSS Modules (https://github.com/css-modules/css-modules)
// using the extension .module.css
{
test: cssModuleRegex,
use: getStyleLoaders({
importLoaders: 1,
modules: true,
getLocalIdent: getCSSModuleLocalIdent,
}),
},
// Opt-in support for SASS (using .scss or .sass extensions).
// Chains the sass-loader with the css-loader and the style-loader
// to immediately apply all styles to the DOM.
// By default we support SASS Modules with the
// extensions .module.scss or .module.sass
{
test: sassRegex,
exclude: sassModuleRegex,
use: getStyleLoaders({ importLoaders: 2 }, 'sass-loader'),
},
// Adds support for CSS Modules, but using SASS
// using the extension .module.scss or .module.sass
{
test: sassModuleRegex,
use: getStyleLoaders(
{
importLoaders: 2,
modules: true,
getLocalIdent: getCSSModuleLocalIdent,
},
'sass-loader'
),
},
// "file" loader makes sure those assets get served by WebpackDevServer.
// When you `import` an asset, you get its (virtual) filename.
// In production, they would get copied to the `build` folder.
// This loader doesn't use a "test" so it will catch all modules
// that fall through the other loaders.
{
// Exclude `js` files to keep "css" loader working as it injects
// its runtime that would otherwise be processed through "file" loader.
// Also exclude `html` and `json` extensions so they get processed
// by webpacks internal loaders.
exclude: [/\.(js|jsx)$/, /\.html$/, /\.json$/],
loader: require.resolve('file-loader'),
options: {
name: 'static/media/[name].[hash:8].[ext]',
},
},
],
},
// ** STOP ** Are you adding a new loader?
// Make sure to add the new loader(s) before the "file" loader.
],
},
plugins: [
// Generates an `index.html` file with the <script> injected.
new HtmlWebpackPlugin({
inject: true,
template: paths.appHtml,
}),
// Makes some environment variables available in index.html.
// The public URL is available as %PUBLIC_URL% in index.html, e.g.:
// <link rel="shortcut icon" href="%PUBLIC_URL%/favicon.ico">
// In development, this will be an empty string.
new InterpolateHtmlPlugin(HtmlWebpackPlugin, env.raw),
// This gives some necessary context to module not found errors, such as
// the requesting resource.
new ModuleNotFoundPlugin(paths.appPath),
// Makes some environment variables available to the JS code, for example:
// if (process.env.NODE_ENV === 'development') { ... }. See `./env.js`.
new webpack.DefinePlugin(env.stringified),
// This is necessary to emit hot updates (currently CSS only):
new webpack.HotModuleReplacementPlugin(),
// Watcher doesn't work well if you mistype casing in a path so we use
// a plugin that prints an error when you attempt to do this.
// See https://github.com/facebook/create-react-app/issues/240
new CaseSensitivePathsPlugin(),
// If you require a missing module and then `npm install` it, you still have
// to restart the development server for Webpack to discover it. This plugin
// makes the discovery automatic so you don't have to restart.
// See https://github.com/facebook/create-react-app/issues/186
new WatchMissingNodeModulesPlugin(paths.appNodeModules),
// Moment.js is an extremely popular library that bundles large locale files
// by default due to how Webpack interprets its code. This is a practical
// solution that requires the user to opt into importing specific locales.
// https://github.com/jmblog/how-to-optimize-momentjs-with-webpack
// You can remove this if you don't use Moment.js:
new webpack.IgnorePlugin(/^\.\/locale$/, /moment$/),
// Generate a manifest file which contains a mapping of all asset filenames
// to their corresponding output file so that tools can pick it up without
// having to parse `index.html`.
new ManifestPlugin({
fileName: 'asset-manifest.json',
publicPath,
}),
],
// Some libraries import Node modules but don't use them in the browser.
// Tell Webpack to provide empty mocks for them so importing them works.
node: {
dgram: 'empty',
fs: 'empty',
net: 'empty',
tls: 'empty',
child_process: 'empty',
},
// Turn off performance processing because we utilize
// our own hints via the FileSizeReporter
performance: false,
};
Error
Failed to compile.
Invalid configuration object. Webpack has been initialised using a configuration object that does not match the API schema.
- configuration.module.rules[3].oneOf[6].use should be one of these:
non-empty string | function | object { loader?, options?, ident?, query? } | function | [non-empty string | function | object { loader?, options?, ident?, query? }]
-> Modifiers applied to the module when rule is matched
Details:
* configuration.module.rules[3].oneOf[3].use should be a string.
* configuration.module.rules[3].oneOf[3].use should be an instance of function
* configuration.module.rules[3].oneOf[3].use should be an object.
* configuration.module.rules[3].oneOf[3].use should be an instance of function
* configuration.module.rules[3].oneOf[3].use[3] should be a string.
* configuration.module.rules[3].oneOf[3].use[3] should be an instance of function
* configuration.module.rules[3].oneOf[3].use[3] has an unknown property 'test'. These properties are valid:
object { loader?, options?, ident?, query? }
* configuration.module.rules[3].oneOf[3].use[3] has an unknown property 'loaders'. These properties are valid:
object { loader?, options?, ident?, query? }
* configuration.module.rules[3].oneOf[3].use[4] should be a string.
* configuration.module.rules[3].oneOf[3].use[4] should be an instance of function
* configuration.module.rules[3].oneOf[3].use[4] has an unknown property 'exclude'. These properties are valid:
object { loader?, options?, ident?, query? }
* configuration.module.rules[3].oneOf[4].use should be a string.
* configuration.module.rules[3].oneOf[4].use should be an instance of function
* configuration.module.rules[3].oneOf[4].use should be an object.
* configuration.module.rules[3].oneOf[4].use should be an instance of function
* configuration.module.rules[3].oneOf[4].use[3] should be a string.
* configuration.module.rules[3].oneOf[4].use[3] should be an instance of function
* configuration.module.rules[3].oneOf[4].use[3] has an unknown property 'test'. These properties are valid:
object { loader?, options?, ident?, query? }
* configuration.module.rules[3].oneOf[4].use[3] has an unknown property 'loaders'. These properties are valid:
object { loader?, options?, ident?, query? }
* configuration.module.rules[3].oneOf[4].use[4] should be a string.
* configuration.module.rules[3].oneOf[4].use[4] should be an instance of function
* configuration.module.rules[3].oneOf[4].use[4] has an unknown property 'exclude'. These properties are valid:
object { loader?, options?, ident?, query? }
* configuration.module.rules[3].oneOf[5].use should be a string.
* configuration.module.rules[3].oneOf[5].use should be an instance of function
* configuration.module.rules[3].oneOf[5].use should be an object.
* configuration.module.rules[3].oneOf[5].use should be an instance of function
* configuration.module.rules[3].oneOf[5].use[3] should be a string.
* configuration.module.rules[3].oneOf[5].use[3] should be an instance of function
* configuration.module.rules[3].oneOf[5].use[3] has an unknown property 'test'. These properties are valid:
object { loader?, options?, ident?, query? }
* configuration.module.rules[3].oneOf[5].use[3] has an unknown property 'loaders'. These properties are valid:
object { loader?, options?, ident?, query? }
* configuration.module.rules[3].oneOf[5].use[4] should be a string.
* configuration.module.rules[3].oneOf[5].use[4] should be an instance of function
* configuration.module.rules[3].oneOf[5].use[4] has an unknown property 'exclude'. These properties are valid:
object { loader?, options?, ident?, query? }
* configuration.module.rules[3].oneOf[6].use should be a string.
* configuration.module.rules[3].oneOf[6].use should be an instance of function
* configuration.module.rules[3].oneOf[6].use should be an object.
* configuration.module.rules[3].oneOf[6].use should be an instance of function
* configuration.module.rules[3].oneOf[6].use[3] should be a string.
* configuration.module.rules[3].oneOf[6].use[3] should be an instance of function
* configuration.module.rules[3].oneOf[6].use[3] has an unknown property 'test'. These properties are valid:
object { loader?, options?, ident?, query? }
* configuration.module.rules[3].oneOf[6].use[3] has an unknown property 'loaders'. These properties are valid:
object { loader?, options?, ident?, query? }
* configuration.module.rules[3].oneOf[6].use[4] should be a string.
* configuration.module.rules[3].oneOf[6].use[4] should be an instance of function
* configuration.module.rules[3].oneOf[6].use[4] has an unknown property 'exclude'. These properties are valid:
object { loader?, options?, ident?, query? }
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! data-engine#0.1.0 start: `node scripts/start.js`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the data-engine#0.1.0 start script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
npm ERR! A complete log of this run can be found in:

Answer 1

You can't specify multiple loaders in a oneOf configuration. As the error shows, you can only use these object properties:
{ loader?, options?, ident?, query? }
This code is difficult to follow, buuut
You don't need a test: key because this is already inside a block that has a test: sassModuleRegex....
I think you don't need to add anything to the getStyleLoaders function at all. Remove your changes from there. I think all you need is your specific regex and configurations:
// Adds support for CSS Modules, but using SASS
// using the extension .module.scss or .module.sass
{
test: sassModuleRegex,
use: getStyleLoaders(
{
importLoaders: 2,
modules: true,
getLocalIdent: getCSSModuleLocalIdent,
},
'sass-loader'
),
},