Develop Reference

webpack-dev-server doesn't update HTML auto?

I'm using webpack-dev-server with webpack v5 and for a reason when I made changes in my CSS and js it updated on time as expected but for HTML files I have to refresh my browser manually to see the new complied version .
src
|-index.html
|-index.js
webpack.config.js
const path = require("path");
const htmlWebpackPlugin = require("html-webpack-plugin");
module.exports = {
mode: "development",
output: {
clean: true,
filename: "bundel.js",
path: path.resolve(__dirname, "dist"),
},
plugins: [
new htmlWebpackPlugin({
filename: "index.html",
template: path.resolve(__dirname, "src", "index.html"),
}),
],
};
my package.json devDependencies
"devDependencies": {
"html-webpack-plugin": "^5.5.0",
"webpack": "^5.70.0",
"webpack-cli": "^4.9.2",
"webpack-dev-server": "^4.7.4"
}
I start my server with npx webpack serve --open
I added CSS file and its relative CSS loaders for testing and removed it after I make sure it work and just HTML is the problem
you can replicate the problem when you change the index.html content

The problem is webpack-dev-server doesn't watch HTML files by default
so I found two solutions for this :
The first solution is built-in throw devServer by adding watchFiles:
devServer: {
watchFiles: ["src/*.html"],
hot: true,
},
The second solution using an external plugin called browser-sync-webpack-plugin

Try to use the DevServer option to reload the page and compress all.
Instead of running npx webpack serve --open run npm run start using this script config:
"scripts": {
"start": "webpack-dev-server",
"build": "webpack",
"test": "echo \"Error: no test specified\" && exit 1"
},
And try to use this base config for your webpack.config.js
const path = require('path');
const HtmlWebpackPlugin = require('html-webpack-plugin');
module.exports = {
// Default settings
mode:'development',
devtool:'inline-source-map',
entry:{
main: path.join(__dirname,'src','index.js')
},
output:{
filename:'index.js',
path: path.resolve(__dirname,'dist'),
clean:true,
},
// Loaders
module:{
// JavaScript
rules:[
{
test: /\.js$/i,
use:{
loader:'babel-loader',
options:{
"presets":['#babel/preset-react']
}}
},
// Css
{
test: /\.css$/i, use:['style-loader','css-loader']
}
]
},
// Plugins
plugins:[
new HtmlWebpackPlugin({
template: path.join(__dirname,'public','index.html') ,
filename:'index.html'
})
],
// DevServer
devServer:{
port:8080,
open:true,
compress:true,
hot:true,
liveReload:true,
}
};

Remove console on browser when loading react app with npm start via webpack-dev-server

So after npm build and npm run , why does my react application open with console on the screen? It was not happening when my packages were "webpack-cli": "^4.2.0" and "webpack-dev-server": "^3.11.1". Upgrading them is causing this issue. How can we fix this?
My package.json contains (devDependencies)
"clean-webpack-plugin": "^3.0.0",
"copy-webpack-plugin": "^7.0.0",
"webpack": "^5.11.0",
"webpack-bundle-analyzer": "^4.3.0",
"webpack-cli": "^4.9.2",
"webpack-dev-server": "^4.7.3",
"webpack-manifest-plugin": "2.2.0",
"webpack-merge": "^5.7.2"
"eslint-webpack-plugin": "^2.1.0",
"html-webpack-plugin": "5.3.2",
"scripts": {
"start": "webpack serve --config config/webpack.config.js --env TARGET_ENV=development --env app=web --port 3000",
"build": "webpack --config config/webpack.config.js --env TARGET_ENV=production",
"build:staging": "webpack --config config/webpack.config.js --env TARGET_ENV=staging"
}
webpack.config.js
const { merge } = require("webpack-merge");
//const commonConfig = require("./webpack.common.js");
const paths = require("./paths");
const webpack = require("webpack");
const { CleanWebpackPlugin } = require("clean-webpack-plugin");
const CopyWebpackPlugin = require("copy-webpack-plugin");
const HtmlWebpackPlugin = require("html-webpack-plugin");
const ESLintPlugin = require("eslint-webpack-plugin");
const getClientEnvironment = require("./env");
module.exports = (env) => {
const targetEnv = env.TARGET_ENV;
const mode = targetEnv === "development" ? "development" : "production";
process.env.NODE_ENV = mode;
// Source maps are resource heavy and can cause out of memory issue for large source files.
// const shouldUseSourceMap = webpackEnv === "development";
const commonConfig = {
mode: mode,
// Where webpack looks to start building the bundle
entry: {
web: paths.src + "/web.tsx",
},
// Where webpack outputs the assets and bundles
resolve: {
extensions: [".tsx", ".ts", ".js"],
fallback: {
util: require.resolve("util/"),
},
modules: ["node_modules", "./src"],
},
// Customize the webpack build process
plugins: [
new webpack.ProvidePlugin({
process: "process/browser",
}),
// Makes some environment variables available to the JS code, for example:
// if (process.env.NODE_ENV === 'production') { ... }. See `./env.js`.
// It is absolutely essential that NODE_ENV is set to production
// during a production build.
// Otherwise React will be compiled in the very slow development mode.
new webpack.DefinePlugin(getClientEnvironment(targetEnv).stringified),
new webpack.IgnorePlugin({
resourceRegExp: /^\.\/locale$/,
contextRegExp: /moment$/,
}),
// Removes/cleans build folders and unused assets when rebuilding
new CleanWebpackPlugin(),
// Copies files from target to destination folder
new CopyWebpackPlugin({
patterns: [
{
from: paths.public,
to: paths.build,
globOptions: {
ignore: ["**/*.html"],
},
},
{
from: paths.appPath + "/web.config",
to: paths.build,
},
],
}),
// Generates an HTML file from a template
// Generates deprecation warning: https://github.com/jantimon/html-webpack-plugin/issues/1501
new HtmlWebpackPlugin({
//favicon: paths.src + "/images/favicon.png",
template: paths.public + "/web.html", // template file
chunks: ["vendor", "web"],
filename: "web.html", // output file
inject: true,
}),
new HtmlWebpackPlugin({
template: paths.public + "/crossplatform.html", // template file
chunks: ["vendor", "crossplatform"],
filename: "crossplatform.html", // output file
inject: true,
}),
new ESLintPlugin({
// Plugin options
extensions: ["js", "jsx", "ts", "tsx"],
}),
],
// Determine how modules within the project are treated
module: {
rules: [
// JavaScript: Use Babel to transpile JavaScript files
{
test: /\.(ts|js)x?$/,
include: paths.src,
//exclude: /node_modules/,
loader: "babel-loader",
options: {
cacheDirectory: true,
// See #6846 for context on why cacheCompression is disabled
cacheCompression: false,
// Babel sourcemaps are needed for debugging into node_modules
// code. Without the options below, debuggers like VSCode
// show incorrect code and set breakpoints on the wrong lines.
//sourceMaps: shouldUseSourceMap,
//inputSourceMap: shouldUseSourceMap,
},
},
// Images: Copy image files to build folder
{ test: /\.(?:ico|gif|png|jpg|jpeg)$/i, type: "asset/resource" },
// Fonts and SVGs: Inline files
{ test: /\.(woff(2)?|eot|ttf|otf|svg|)$/, type: "asset/inline" },
],
},
};
const envConfig = require(`./webpack.${mode}.js`)({ app: env.app });
return merge(commonConfig, envConfig);
};
webpack.development.js
const webpack = require("webpack");
const paths = require("./paths");
module.exports = (args) => {
return {
// Control how source maps are generated
devtool: "cheap-module-source-map",
output: {
//path: paths.build,
publicPath: "./",
filename: "[name].js",
},
// Needed because of an issue with webpack dev server HMR with Webpack https://github.com/webpack/webpack-dev-server/issues/2758
target: "web",
// Spin up a server for quick development
devServer: {
historyApiFallback: {
index: "/" + args.app + ".html",
},
open: true,
devMiddleware: {
publicPath: "/",
},
hot: true,
// By default files from `contentBase` will not trigger a page reload.
// watchContentBase: true,
},
module: {
rules: [
// Styles: Inject CSS into the head with source maps
{
test: /\.(css)$/,
use: [
"style-loader",
{
loader: "css-loader",
//options: { sourceMap: true },
},
],
},
],
},
};
};

webpack imported module is not a constructor

I created a small JS module which I intend to make an npm package, but for now is just on GitHub. This module is written in ES6 and SCSS, and is thus relying on webpack and babel for transpilation.
To test it, I created a separate project with a similar setup (webpack and babel). After npm installing my module, when trying to import it into my index.js, I get the following error in Chrome Developer Tools: (with x being my module's name)
index.js:11 Uncaught TypeError: x__WEBPACK_IMPORTED_MODULE_1___default.a is not a constructor
at eval (index.js:11)
at Object../src/index.js (main.js:368)
at __webpack_require__ (main.js:20)
at eval (webpack:///multi_(:8081/webpack)-dev-server/client?:2:18)
at Object.0 (main.js:390)
at __webpack_require__ (main.js:20)
at main.js:69
at main.js:72
I've looked through countless answers and tried countless solutions, to no avail. My module's setup is as follows.
.babelrc
{
"presets": [
["env", {
"targets": {
"browsers": ["ie >= 11"]
}
}]
],
"plugins": [
"transform-es2015-modules-commonjs",
"transform-class-properties"
]
}
webpack.common.js
const path = require('path')
const ExtractTextPlugin = require('extract-text-webpack-plugin')
const HtmlWebpackPlugin = require('html-webpack-plugin')
const cleanWebpackPlugin = require('clean-webpack-plugin')
const baseSCSS = new ExtractTextPlugin('main/_base.css')
const themeSCSS = new ExtractTextPlugin('main/_theme.css')
module.exports = {
entry: {
example: [
path.join(__dirname, 'src', 'example', 'index.js')
],
main: [
'idempotent-babel-polyfill',
path.join(__dirname, 'src', 'index.js')
]
},
output: {
path: path.join(__dirname, 'dist'),
filename: path.join('[name]', 'index.js')
},
module: {
rules: [
{
test: /\.js$/,
exclude: /node_modules/,
use: {
loader: 'babel-loader',
}
},
{
test: /\.scss$/,
use: ExtractTextPlugin.extract(
{
fallback: 'style-loader',
use: ['css-loader', 'sass-loader']
}
)
},
{
test: /\_base-scss$/,
use: baseSCSS.extract(
{
fallback: 'style-loader',
use: ['css-loader', 'sass-loader']
}
)
},
{
test: /\_theme-scss$/,
use: themeSCSS.extract(
{
fallback: 'style-loader',
use: ['css-loader', 'sass-loader']
}
)
}
]
},
plugins: [
new cleanWebpackPlugin('dist', {}),
new ExtractTextPlugin({ filename: path.join('example', 'style.css') }),
baseSCSS,
themeSCSS,
new HtmlWebpackPlugin({
inject: false,
hash: true,
template: path.join(__dirname, 'src', 'example', 'index.html'),
filename: path.join('example', 'index.html')
})
]
}
webpack.prod.js
const merge = require('webpack-merge')
const UglifyJSPlugin = require('uglifyjs-webpack-plugin')
const webpack = require('webpack')
const common = require('./webpack.common.js')
module.exports = merge(common, {
plugins: [
new UglifyJSPlugin({
sourceMap: true
}),
new webpack.DefinePlugin({
'process.env.NODE_ENV': JSON.stringify('production')
})
],
mode: 'production'
})
package.json
{
"name": "my-module-name",
"version": "1.0.0-beta.1",
"description": "",
"main": "dist/main/index.js",
"scripts": {
"start": "webpack-dev-server --config webpack.dev.js",
"server": "node src/server",
"format": "prettier-standard 'src/**/*.js'",
"lint": "eslint src",
"build": "webpack --config webpack.prod.js",
"test": "echo \"Error: no test specified\" && exit 1"
},
"author": "Liran",
"license": "ISC",
"devDependencies": {
"babel-core": "^6.26.0",
"babel-eslint": "^8.2.3",
"babel-loader": "^7.1.4",
"babel-plugin-transform-class-properties": "^6.24.1",
"babel-plugin-transform-es2015-modules-commonjs": "^6.26.2",
"babel-preset-env": "^1.7.0",
"clean-webpack-plugin": "^0.1.19",
"css-loader": "^0.28.11",
"eslint": "^4.19.1",
"extract-text-webpack-plugin": "^4.0.0-beta.0",
"html-webpack-plugin": "^3.2.0",
"idempotent-babel-polyfill": "^0.1.1",
"node-sass": "^4.9.0",
"prettier-standard": "^8.0.1",
"sass-loader": "^7.0.1",
"style-loader": "^0.21.0",
"uglifyjs-webpack-plugin": "^1.2.5",
"webpack": "^4.6.0",
"webpack-cli": "^2.0.15",
"webpack-dev-middleware": "^3.1.3",
"webpack-dev-server": "^3.1.3",
"webpack-merge": "^4.1.2"
}
}
Any help/pointers would be greatly appreciated. If you need more information, please let me know.

If you are not the library author and are having a problem consuming another library, you may be seeing an error like this:
TypeError: [LIBRARY_NAME]__WEBPACK_IMPORTED_MODULE_3__ is not a constructor
If that's the case, you may be importing the library incorrectly in your code (it may be a problem with default exports). Double check the library docs for usage.
It may be as simple as changing this:
import Foo from 'some-library/Foo';
to this:
import { Foo } from 'some-library';

It is not working because it is missing libraryTarget and library properties. By doing that webpack know which format of module you would like to create, i.e: commonjs (module.exports) or es (export).
I would do something like:
...
output: {
path: path.join(__dirname, 'dist'),
filename: path.join('[name]', 'index.js'),
library: "my-library",
libraryTarget: "umd" // exposes and know when to use module.exports or exports.
},
...

Besides setting the libraryTarget, it may also be necessary to move the export in the JavaScript file to the default.
function MyClassName() {
...
}
export default MyClassName;
And then in the webpack configuration the library type umd ...
(Note that I have used the newer library.type instead the older libraryTarget (see https://webpack.js.org/configuration/output/#outputlibrarytarget).
const path = require('path');
module.exports = {
mode: "production",
entry: '../wherever/MyClassName.js',
output: {
library: {
name: "MyClassName",
type: "umd", // see https://webpack.js.org/configuration/output/#outputlibrarytype
export: "default", // see https://github.com/webpack/webpack/issues/8480
},
filename: 'MyClassName.min.js',
path: path.resolve(__dirname, '../wherever/target/')
},
optimization: {
minimize: true
}
};
The export default makes the class available in JavaScript like the file was embedded directly, i.e.,
<script type="text/javascript" src="MyClassName.min.js"></script>
<script type="text/javascript">
<!--
var myInstance = new MyClassName();
// -->
</script>
Disclaimer: I added this answer even though the original question is three years old by now. After encountering the "is not a constructor" issue, it took me hours of searching to find the default solution. And that was the second time, I searched and found it :D

Cf. David Calhoun's answer, if you run into this with a third-party library, you may be trying to import a CommonJS module as an ECMAScript module. The workaround there seems to be to use require instead of import, e.g., instead of
import { Foo } from 'bar'
you need to write
const Foo = require('bar')
(There may be a more elegant way to handle this, but this is what worked for me.)

For me, it was the cache issue. Just cleared the cookies, cache data and closed, reopened the browser. It worked.

In my case, the error was being caused in React when trying to invoke JS's built-in Error constructor, or in other words, basically when calling throw new Error("something").
On inspection of my code, I realised I had a component called Error in my project which was being imported into the same file. The name clash between this component and JS's built-in Error constructor was causing the error mentioned in the question.

In case something is using wepack 5 + babel 7
"webpack": "5.73.0",
"#babel/core": "7.4.4",
"#babel/preset-env": "7.4.4",
"babel-loader": "8.0.5",
AND want to use class instead function, this worked for me:
class Person {
constructor(fname, lname, age, address) {
this.fname = fname;
this.lname = lname;
this.age = age;
this.address = address;
}
get fullname() {
return this.fname +"-"+this.lname;
}
}
export default Person;
In my case .babelrc was not necesary

tl;dr
Make sure that you import properly through index files.
Explanation
For me, this error was caused by importing through index files. I had multiple directories with their index.ts files that exported all the files inside the directory. These index files were accumulated/reexported by a main index.ts file so everything can be imported through it.
src/
├── index.ts
├── module1/
│ ├── index.ts
│ ├── file1.ts
│ └── file2.ts
└── module2/
├── index.ts
├── file3.ts
└── file4.ts
In file4.ts I had an import like this:
import { file1Class, file2Class, file3Class } from "src";
I had to split it into two separate imports:
import { file1Class, file2Class } from "src/module1";
import { file3Class } from "src/module2";

ReactJS linting (eslint) and transpiling (babel) error on shared code using monorepo (Lerna + Yarn Workspaces)

I´m building a monorepo using yarn workspaces, lerna and 2 different projects:
ux - a React component library built using create-react-app
auth - a React application that uses ux library built using create-react-app and then ejected (the ejection was done to try to solve the current linting and transpiling error).
My monorepo setup is:
project
|-------- node_modules
|-------- lerna.json
|-------- package.json
|-------- packages
|----------- auth
|------- node_modules
|------- src
|------- packages.json
|----------- ux
|------- node_modules
|------- src
|------- packages.json
lerna.json:
{
"lerna": "2.9.0",
"npmClient": "yarn",
"useWorkspaces": true,
"packages": [
"packages/*"
],
"version": "3.0.0"
}
Lerna root package.json:
{
"name": "myorganization",
"version": "3.0.0",
"license": "UNLICENSED",
"workspaces": ["packages/*"],
"private": true,
"scripts": {
"clean": "lerna clean -f --yes && rm -rf node_modules",
"reset": "yarn run clean && yarn",
"auth": "cd packages/auth && yarn start"
},
"devDependencies": {
"lerna": "^2.9.0"
}
}
ux package.json: (ux was not ejected)
{
"name": "#myorganization/ux",
"version": "3.0.0",
"author": "Me",
"private": true,
"license": "UNLICENSED",
"dependencies": {
"react": "^16.2.0",
"react-dom": "^16.2.0",
"react-scripts": "2.0.0-next.9754a231"
},
"scripts": {
"start": "react-scripts start",
"build": "react-scripts build",
"test": "react-scripts test --env=jsdom",
"eject": "react-scripts eject"
},
"browserslist": {
"development": [
"last 2 chrome versions",
"last 2 firefox versions",
"last 2 edge versions"
],
"production": [
">1%",
"last 4 versions",
"Firefox ESR",
"not ie < 11"
]
},
"devDependencies": {
"eslint": "^4.19.0",
"eslint-plugin-react": "^7.7.0"
}
}
auth package.json:
{
"name": "#myorganization/auth",
"version": "3.0.0",
"private": true,
"author": "Me",
"license": "UNLICENSED",
"dependencies": {
"#myorganization/ux": "^3.0.0",
"#babel/core": "7.0.0-beta.38",
"#babel/runtime": "7.0.0-beta.38",
"autoprefixer": "7.2.5",
"babel-core": "7.0.0-bridge.0",
"babel-eslint": "8.2.1",
"babel-jest": "22.1.0",
"babel-loader": "8.0.0-beta.0",
"babel-preset-react-app": "4.0.0-next.9754a231",
"case-sensitive-paths-webpack-plugin": "2.1.1",
"chalk": "2.3.0",
"css-loader": "0.28.9",
"dotenv": "4.0.0",
"dotenv-expand": "4.0.1",
"eslint-config-react-app": "3.0.0-next.9754a231",
"eslint-loader": "1.9.0",
"eslint-plugin-flowtype": "2.41.0",
"eslint-plugin-import": "2.8.0",
"eslint-plugin-jsx-a11y": "6.0.3",
"extract-text-webpack-plugin": "3.0.2",
"file-loader": "1.1.6",
"fs-extra": "5.0.0",
"html-webpack-plugin": "2.30.1",
"identity-obj-proxy": "3.0.0",
"jest": "22.1.2",
"object-assign": "4.1.1",
"postcss-flexbugs-fixes": "3.2.0",
"postcss-loader": "2.0.10",
"promise": "8.0.1",
"raf": "3.4.0",
"react": "^16.2.0",
"react-dev-utils": "6.0.0-next.9754a231",
"react-dom": "^16.2.0",
"react-router-dom": "^4.2.2",
"style-loader": "0.19.1",
"svgr": "1.6.0",
"sw-precache-webpack-plugin": "0.11.4",
"thread-loader": "1.1.2",
"uglifyjs-webpack-plugin": "1.1.6",
"url-loader": "0.6.2",
"webpack": "3.10.0",
"webpack-dev-server": "2.11.0",
"webpack-manifest-plugin": "1.3.2",
"whatwg-fetch": "2.0.3"
},
"scripts": {
"start": "node scripts/start.js",
"build": "node scripts/build.js",
"test": "node scripts/test.js --env=jsdom"
},
"browserslist": {
"development": [
"last 2 chrome versions",
"last 2 firefox versions",
"last 2 edge versions"
],
"production": [
">1%",
"last 4 versions",
"Firefox ESR",
"not ie < 11"
]
},
"jest": {
"collectCoverageFrom": [
"src/**/*.{js,jsx,mjs}"
],
"setupFiles": [
"<rootDir>/config/polyfills.js"
],
"testMatch": [
"<rootDir>/src/**/__tests__/**/*.{js,jsx,mjs}",
"<rootDir>/src/**/?(*.)(spec|test).{js,jsx,mjs}"
],
"testEnvironment": "node",
"testURL": "http://localhost",
"transform": {
"^.+\\.(js|jsx|mjs)$": "<rootDir>/node_modules/babel-jest",
"^.+\\.css$": "<rootDir>/config/jest/cssTransform.js",
"^(?!.*\\.(js|jsx|mjs|css|json)$)": "<rootDir>/config/jest/fileTransform.js"
},
"transformIgnorePatterns": [
"'[/\\\\]node_modules[/\\\\](?!' + paths.allLernaModules.join('|') + ').*\\.(js|jsx|mjs)$'",
"^.+\\.module\\.css$"
],
"moduleNameMapper": {
"^react-native$": "react-native-web",
"^.+\\.module\\.css$": "identity-obj-proxy"
},
"moduleFileExtensions": [
"web.js",
"mjs",
"js",
"json",
"web.jsx",
"jsx",
"node"
]
},
"babel": {
"presets": [
"react-app"
]
},
"eslintConfig": {
"extends": "react-app"
},
"devDependencies": {
"eslint": "^4.19.0",
"eslint-plugin-react": "^7.7.0"
}
}
Then I´ve changed the create-react-app created config/paths to grab the referenced packages:
"use strict";
const path = require("path");
const fs = require("fs");
const url = require("url");
// Make sure any symlinks in the project folder are resolved:
// https://github.com/facebookincubator/create-react-app/issues/637
const appDirectory = fs.realpathSync(process.cwd());
const resolveApp = relativePath => path.resolve(appDirectory, relativePath);
const envPublicUrl = process.env.PUBLIC_URL;
function ensureSlash(path, needsSlash) {
const hasSlash = path.endsWith("/");
if (hasSlash && !needsSlash) {
return path.substr(path, path.length - 1);
} else if (!hasSlash && needsSlash) {
return `${path}/`;
} else {
return path;
}
}
const getPublicUrl = appPackageJson =>
envPublicUrl || require(appPackageJson).homepage;
// We use `PUBLIC_URL` environment variable or "homepage" field to infer
// "public path" at which the app is served.
// Webpack needs to know it to put the right <script> hrefs into HTML even in
// single-page apps that may serve index.html for nested URLs like /todos/42.
// We can't use a relative path in HTML because we don't want to load something
// like /todos/42/static/js/bundle.7289d.js. We have to know the root.
function getServedPath(appPackageJson) {
const publicUrl = getPublicUrl(appPackageJson);
const servedUrl =
envPublicUrl || (publicUrl ? url.parse(publicUrl).pathname : "/");
return ensureSlash(servedUrl, true);
}
// config after eject: we're in ./config/
module.exports = {
dotenv: resolveApp(".env"),
appPath: resolveApp("."),
appBuild: resolveApp("build"),
appPublic: resolveApp("public"),
appHtml: resolveApp("public/index.html"),
appIndexJs: resolveApp("src/index.js"),
appPackageJson: resolveApp("package.json"),
appSrc: resolveApp("src"),
yarnLockFile: resolveApp("yarn.lock"),
testsSetup: resolveApp("src/setupTests.js"),
appNodeModules: resolveApp("node_modules"),
publicUrl: getPublicUrl(resolveApp("package.json")),
servedPath: getServedPath(resolveApp("package.json"))
};
module.exports.lernaRoot = path
.resolve(resolveApp("."), "../")
.endsWith("packages")
? path.resolve(resolveApp("."), "../../")
: resolveApp(".");
module.exports.appLernaModules = [];
module.exports.appLernaNodeModules = path.join(
module.exports.lernaRoot,
"node_modules"
);
fs.readdirSync(module.exports.appLernaNodeModules).forEach(folderName => {
if (folderName === "react-scripts") return;
if (folderName.substr(0, 1) === ".") return;
let fullName = path.join(module.exports.appLernaNodeModules, folderName);
if (folderName.substr(0, 1) === "#" && fs.lstatSync(fullName).isDirectory()) {
fs.readdirSync(fullName).forEach(subFolderName => {
let subFullName = path.join(fullName, subFolderName);
if (fs.lstatSync(subFullName).isSymbolicLink()) {
let src = fs.realpathSync(subFullName);
module.exports.appLernaModules.push(src);
}
});
}
if (fs.lstatSync(fullName).isSymbolicLink()) {
module.exports.appLernaModules.push(fs.realpathSync(fullName));
}
});
And changed the create-react-app original webpack.config.dev to:
"use strict";
const autoprefixer = require("autoprefixer");
const path = require("path");
const webpack = require("webpack");
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 eslintFormatter = require("react-dev-utils/eslintFormatter");
const ModuleScopePlugin = require("react-dev-utils/ModuleScopePlugin");
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);
// Options for PostCSS as we reference these options twice
// Adds vendor prefixing based on your specified browser support in
// package.json
const postCSSLoaderOptions = {
// Necessary for external CSS imports to work
// https://github.com/facebookincubator/create-react-app/issues/2677
ident: "postcss",
plugins: () => [
require("postcss-flexbugs-fixes"),
autoprefixer({
flexbox: "no-2009"
})
]
};
console.log(paths.appLernaModules.concat(paths.appSrc));
// 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 = {
// You may want 'eval' instead if you prefer to see the compiled output in DevTools.
// See the discussion in https://github.com/facebookincubator/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.
// The first two entry points enable "hot" CSS and auto-refreshes for JS.
entry: [
// We ship a few polyfills by default:
require.resolve("./polyfills"),
// 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: publicPath,
// Point sourcemap entries to original disk location (format as URL on Windows)
devtoolModuleFilenameTemplate: info =>
path.resolve(info.absoluteResourcePath).replace(/\\/g, "/")
},
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/facebookincubator/create-react-app/issues/253
modules: ["node_modules", paths.appNodeModules].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/facebookincubator/create-react-app/issues/290
// `web` extension prefixes have been added for better support
// for React Native Web.
extensions: [".web.js", ".mjs", ".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: [
// 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])
]
},
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|mjs)$/,
enforce: "pre",
use: [
{
options: {
formatter: eslintFormatter,
eslintPath: require.resolve("eslint")
},
loader: require.resolve("eslint-loader")
}
],
include: paths.appLernaModules.concat(paths.appSrc)
},
{
// "oneOf" will traverse all following loaders until one will
// match the requirements. When no loader matches it will fall
// back to the "file" loader at the end of the loader list.
oneOf: [
// "url" loader works like "file" loader except that it embeds assets
// smaller than specified limit in bytes as data URLs to avoid requests.
// A missing `test` is equivalent to a match.
{
test: [/\.bmp$/, /\.gif$/, /\.jpe?g$/, /\.png$/],
loader: require.resolve("url-loader"),
options: {
limit: 10000,
name: "static/media/[name].[hash:8].[ext]"
}
},
// Process application JS with Babel.
// The preset includes JSX, Flow, and some ESnext features.
{
test: /\.(js|jsx|mjs)$/,
include: paths.appLernaModules.concat(paths.appSrc),
use: [
// This loader parallelizes code compilation, it is optional but
// improves compile time on larger projects
require.resolve("thread-loader"),
{
loader: require.resolve("babel-loader"),
options: {
// 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,
highlightCode: true
}
}
]
},
// Process any JS outside of the app with Babel.
// Unlike the application JS, we only compile the standard ES features.
{
test: /\.js$/,
use: [
// This loader parallelizes code compilation, it is optional but
// improves compile time on larger projects
require.resolve("thread-loader"),
{
loader: require.resolve("babel-loader"),
options: {
babelrc: false,
compact: false,
presets: [
require.resolve("babel-preset-react-app/dependencies")
],
cacheDirectory: true,
highlightCode: true
}
}
]
},
// "postcss" loader applies autoprefixer to our CSS.
// "css" loader resolves paths in CSS and adds assets as dependencies.
// "style" loader turns CSS into JS modules that inject <style> tags.
// In production, we use a plugin to extract that CSS to a file, but
// in development "style" loader enables hot editing of CSS.
// By default we support CSS Modules with the extension .module.css
{
test: /\.css$/,
exclude: /\.module\.css$/,
use: [
require.resolve("style-loader"),
{
loader: require.resolve("css-loader"),
options: {
importLoaders: 1
}
},
{
loader: require.resolve("postcss-loader"),
options: postCSSLoaderOptions
}
]
},
// Adds support for CSS Modules (https://github.com/css-modules/css-modules)
// using the extension .module.css
{
test: /\.module\.css$/,
use: [
require.resolve("style-loader"),
{
loader: require.resolve("css-loader"),
options: {
importLoaders: 1,
modules: true,
localIdentName: "[path]__[name]___[local]"
}
},
{
loader: require.resolve("postcss-loader"),
options: postCSSLoaderOptions
}
]
},
// Allows you to use two kinds of imports for SVG:
// import logoUrl from './logo.svg'; gives you the URL.
// import { ReactComponent as Logo } from './logo.svg'; gives you a component.
{
test: /\.svg$/,
use: [
{
loader: require.resolve("babel-loader"),
options: {
cacheDirectory: true
}
},
require.resolve("svgr/webpack"),
{
loader: require.resolve("file-loader"),
options: {
name: "static/media/[name].[hash:8].[ext]"
}
}
]
},
// "file" loader makes sure those assets get served by WebpackDevServer.
// When you `import` an asset, you get its (virtual) filename.
// In production, they would get copied to the `build` folder.
// This loader doesn't use a "test" so it will catch all modules
// that fall through the other loaders.
{
// Exclude `js` files to keep "css" loader working as it injects
// its runtime that would otherwise be processed through "file" loader.
// Also exclude `html` and `json` extensions so they get processed
// by webpacks internal loaders.
exclude: [/\.(js|jsx|mjs)$/, /\.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: [
// 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(env.raw),
// Generates an `index.html` file with the <script> injected.
new HtmlWebpackPlugin({
inject: true,
template: paths.appHtml
}),
// Add module names to factory functions so they appear in browser profiler.
new webpack.NamedModulesPlugin(),
// 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/facebookincubator/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/facebookincubator/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$/, /moment$/)
],
// 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 hints during development because we don't do any
// splitting or minification in interest of speed. These warnings become
// cumbersome.
performance: {
hints: false
}
};
OBS: Repair the console.log() command in the code above to show what is being loaded.
Running, I´m getting the following result:
$ npm start
> #myorganization/auth#3.0.0 start D:\project\packages\auth
> node scripts/start.js
[ 'D:\\project\\packages\\auth',
'D:\\project\\packages\\ux',
'D:\\project\\packages\\auth\\src' ]
Starting the development server...
Failed to compile.
../ux/src/atoms/index.js
Module build failed: Error: No ESLint configuration found.
Commenting the eslint step in webpack.config.dev, I´m getting:
$ npm start
> #myorganization/auth#3.0.0 start D:\project\packages\auth
> node scripts/start.js
[ 'D:\\project\\packages\\auth',
'D:\\project\\packages\\ux',
'D:\\project\\packages\\auth\\src' ]
Starting the development server...
Failed to compile.
../ux/src/atoms/ActivityItem/ActivityItem.js
Syntax error: D:\project\packages\ux\src\atoms\ActivityItem\ActivityItem.js: Support for the experimental syntax 'classProperties' isn't currently enabled (34:20):
32 | class ActivityItem extends Component {
33 |
> 34 | static propTypes = {
| ^
35 | showHeader: PropTypes.bool,
36 | timestamp: PropTypes.number,
37 | username: PropTypes.string,
Add #babel/plugin-proposal-class-properties (https://git.io/vb4SL) to the 'plugins' section of your Babel config to enable transformation.
In short, the shared code is not being either transpiled or linted, and that breaks the whole project. The whole project was done using ES6.

As of react-scripts 2.0 they removed support for monorepos (https://github.com/facebook/create-react-app/issues/1333). However if you scroll to the bottom of the issues page you will see a link to react-workspaces. I've not tried it, but it looks promising. (https://github.com/react-workspaces/react-workspaces-playground)

How to put React in production mode?

I tried using the solution from here but the icon is still read indicating dev mode.
Here is my current file with updates from the answer below:
const path = require('path');
const SRC_DIR = path.join(__dirname, '/client-react/src');
const DIST_DIR = path.join(__dirname, '/client-react/dist');
const webpack = require('webpack')
module.exports = {
entry: `${SRC_DIR}/index.jsx`,
output: {
filename: 'bundle.js',
path: DIST_DIR
},
plugins: [
new webpack.DefinePlugin({'process.env': {NODE_ENV: JSON.stringify('production')} })
],
module: {
loaders: [
{
test: /\.jsx?/,
include: SRC_DIR,
loader: 'babel-loader',
query: {
plugins: ["transform-object-rest-spread", "transform-class-properties"],
presets: ['react', 'es2015']
}
}
]
}
};

If you use Webpack 4, you don't need to change webpack.config.js. It remains the same in both development and production modes.
The only thing needed is in your package.json:
"scripts": {
"dev": "webpack --mode development",
"build": "webpack --mode production"
}
Having this, to create a development bundle:
npm run dev
Production bundle:
npm run build

When you want to build your app in production mode, you should use webpack production shortcut. Like this:
webpack -p
This will enable webpack optimize options to minify your JS. See more detailed explanation of webpack flags on this SO answer.

Webpack plugins need to be put under the plugins key in module.exports.
https://webpack.github.io/docs/using-plugins.html#built-in-plugins
Try this:
module.exports = {
plugins: [
new webpack.DefinePlugin({
'process.env': { NODE_ENV: JSON.stringify('production') }
}),
]
}

Had the same error so to fix it I did this:
package.json
"scripts": {
"build": "NODE_ENV=production webpack --progress --colors",
"start": "NODE_ENV=development webpack-dev-server --progress --colors"
}
webpack.config.js
const env = process.env.NODE_ENV
module.exports = {
plugins: [
new webpack.DefinePlugin({
'process.env.NODE_ENV': JSON.stringify(env)
})
]
}
It should work for sure.
Here I have some configuration that you can try to optimize your build.

This worked for me: run npm run build followed by npm install -g serve and serve -s build