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Application erros while Deploying React app on heroku

I have created a React app and used webpack to bundle it. Now I am trying to deploy the app on heroku. The build is successful but when I try to open the link I get "Application Error". Is it necessary to have server.js file on root level of your react app to delpoy on heroku.
I have modified my webpack and I think it's fine but still the same error.
//here is my webpack.common.js
const webpack = require("webpack");
module.exports = {
entry: "./index.jsx",
module: {
rules: [
{
test: /\.(js|jsx)$/,
exclude: /(node_modules|bower_components)/,
loader: "babel-loader",
options: { presets: ["#babel/env"] }
},
{
test: /\.css$/,
use: ["style-loader", "css-loader"]
}
]
},
resolve: { extensions: ["*", ".js", ".jsx"] },
output: {
path: path.resolve(__dirname, "dist/"),
publicPath: "/dist/",
filename: "bundle.js"
},
plugins: [new webpack.HotModuleReplacementPlugin()]
}
// webpack.dev.js
const path = require('path');
const merge = require('webpack-merge');
const common = require('./webpack.common');
module.exports = merge(common, {
mode:'development',
devtool: 'inline-source-map',
devServer: {
contentBase: path.join(__dirname, "public/"),
port: 3000,
publicPath: "http://localhost:3000/dist/",
hot: true
}
});
I expect the app to get deployed on heroku but I am getting application error.

Navigator undefined on React Typescript Firebase project

I've been googling for a couple hours now and can't seem to resolve my issue.
I have a webpack/React/Typescript/Mobx setup and am attempting to use firebase.
Here is my webpack config: (boilerplate from this repo)
var webpack = require('webpack');
var path = require('path');
// variables
var isProduction = process.argv.indexOf('-p') >= 0;
var sourcePath = path.join(__dirname, './src');
var outPath = path.join(__dirname, './dist');
// plugins
var HtmlWebpackPlugin = require('html-webpack-plugin');
var ExtractTextPlugin = require('extract-text-webpack-plugin');
var WebpackCleanupPlugin = require('webpack-cleanup-plugin');
module.exports = {
context: sourcePath,
entry: {
main: './main.tsx'
},
output: {
path: outPath,
filename: 'bundle.js',
chunkFilename: '[chunkhash].js',
publicPath: '/'
},
target: 'web',
resolve: {
extensions: ['.js', '.ts', '.tsx'],
// Fix webpack's default behavior to not load packages with jsnext:main module
// (jsnext:main directs not usually distributable es6 format, but es6 sources)
mainFields: ['module', 'browser', 'main'],
alias: {
app: path.resolve(__dirname, 'src/app/'),
assets: path.resolve(__dirname, 'src/assets/')
}
},
module: {
rules: [
// .ts, .tsx
{
test: /\.tsx?$/,
use: [
isProduction
? 'ts-loader'
: {
loader: 'babel-loader',
options: {
babelrc: false,
plugins: ['react-hot-loader/babel']
}
},
'ts-loader'
],
// : ['babel-loader?plugins=react-hot-loader/babel&presets=', 'ts-loader'],
exclude: /node_modules/
},
// css
{
test: /\.css$/,
exclude: /node_modules/,
use: ExtractTextPlugin.extract({
fallback: 'style-loader',
use: [
{
loader: 'css-loader',
query: {
modules: true,
sourceMap: !isProduction,
importLoaders: 1,
localIdentName: '[local]__[hash:base64:5]'
}
},
{
loader: 'postcss-loader',
options: {
ident: 'postcss',
plugins: [
require('postcss-import')({ addDependencyTo: webpack }),
require('postcss-url')(),
require('postcss-cssnext')(),
require('postcss-reporter')(),
require('postcss-browser-reporter')({
disabled: isProduction
})
]
}
}
]
})
},
{
test: /\.css$/,
include: /node_modules/,
use: ['style-loader', 'css-loader']
},
// static assets
{ test: /\.html$/, use: 'html-loader' },
{ test: /\.(png|jpg)$/, use: 'url-loader?limit=10000' },
{ test: /\.webm$/, use: 'file-loader' }
]
},
optimization: {
splitChunks: {
name: true,
cacheGroups: {
commons: {
chunks: 'initial',
minChunks: 2
},
vendors: {
test: /[\\/]node_modules[\\/]/,
chunks: 'all',
priority: -10
}
}
},
runtimeChunk: true
},
plugins: [
new WebpackCleanupPlugin(),
new ExtractTextPlugin({
filename: 'styles.css',
disable: !isProduction
}),
new HtmlWebpackPlugin({
template: 'assets/index.html'
})
],
devServer: {
contentBase: sourcePath,
hot: true,
inline: true,
historyApiFallback: {
disableDotRule: true
},
stats: 'minimal'
},
devtool: 'cheap-module-eval-source-map',
node: {
// workaround for webpack-dev-server issue
// https://github.com/webpack/webpack-dev-server/issues/60#issuecomment-103411179
fs: 'empty',
net: 'empty'
}
};
Just by including firebase in my app i relentlessly end up with this error:
Uncaught TypeError: Cannot read property 'navigator' of undefined auth.esm.js?69b5:10
I have tested by including a simple component like so:
import * as React from 'react';
import * as Styles from './styles.css';
import 'app/utils/FirebaseUtil';
interface TestProps {}
export const Test: React.StatelessComponent<TestProps > = () => (
<div className={Styles.root}>
{'Hello World'}
</div>
);
FirebaseUtil:
import * as firebase from 'firebase';
const config = {
apiKey: '**my key here**',
authDomain: '** my domain here **'
};
firebase.initializeApp(config);
export const fbAuth = firebase.auth;
No matter what I seem to do I get the navigator error. Even if i dont export the auth object. As far as I can tell its related to babel-loader adding strict-mode according to this SO question, i think? All other related searches seem to have to do with firebase-ui, which i am not using in any way.
But I have no idea how he manages to turn off strict mode, not to mention the OP is not using typescript and I am using ts-loader in this case. I can't for the life of me figure out how to get it working. Aside from all of this if I do try use the firebase object for auth() for example I get a bunch of warnings from webpack about auth not existing on the firebase object. Totally stumped.

So in case anyone else runs into this problem. It appears it was a package version issue. Im assuming that the package versions specifically included in the boilerplate i used didn't play well with firebase.
I updated typescript, react-hot-loader, and most likely the issue webpack from version 3.0.4 to 4.12.1 and things seem to be working ok now. Also with the updates I now import firebase like so:
import firebase from '#firebase/app';
import '#firebase/auth';
Hope this helps someone.

In my case I fixed this importing functions
import firebase from 'firebase/app'
import 'firebase/functions'
import 'firebase/analytics'

Webpack throws TypeError: Super expression must either be null or a function, not undefined when importing LESS file

I have the following in a file initialize.js:
import App from './components/App';
import './styles/application.less';
document.addEventListener('DOMContentLoaded', () => {
const app = new App();
app.start();
});
In webpack.config.js I have:
'use strict';
const path = require('path');
const webpack = require('webpack');
const merge = require('webpack-merge');
const ProvidePlugin = webpack.ProvidePlugin;
const ModuleConcatenationPlugin = webpack.optimize.ModuleConcatenationPlugin;
const ExtractTextPlugin = require('extract-text-webpack-plugin');
const CopyWebpackPlugin = require('copy-webpack-plugin');
const extractLess = new ExtractTextPlugin({
filename: 'app.css',
});
const webpackCommon = {
entry: {
app: ['./app/initialize']
},
module: {
rules: [{
test: /\.js$/,
exclude: /node_modules/,
use: [{
loader: 'babel-loader?presets[]=es2015'
}]
}, {
test: /\.hbs$/,
use: {
loader: 'handlebars-loader'
}
}, {
test: /\.less$/,
exclude: /node_modules/,
use: extractLess.extract({
use: [{
loader: 'css-loader'
}, {
loader: 'less-loader'
}],
// use style-loader in development
fallback: 'style-loader'
}),
}]
},
output: {
filename: 'app.js',
path: path.join(__dirname, './public'),
publicPath: '/'
},
plugins: [
extractLess,
new CopyWebpackPlugin([{
from: './app/assets/index.html',
to: './index.html'
}]),
new ProvidePlugin({
$: 'jquery',
_: 'underscore'
}),
new ModuleConcatenationPlugin(),
],
};
module.exports = merge(webpackCommon, {
devtool: '#inline-source-map',
devServer: {
contentBase: path.join(__dirname, 'public'),
compress: true,
port: 9000
}
});
I tried removing the the plugins and the contents of application.less, but I keep getting this error:
ERROR in ./node_modules/css-loader!./node_modules/less-loader/dist/cjs.js!./app/styles/application.less
Module build failed: TypeError: Super expression must either be null or a function, not undefined
at ...
# ./app/styles/application.less 4:14-127
# ./app/initialize.js
If I replace that LESS file with a CSS one and update the config it works fine, so I guess the problem has to do with less-loader.
I'm using Webpack 3.4.1, Style Loader 0.18.2, LESS Loader 4.0.5, Extract Text Webpack Plugin 3.0.0 and CSS Loader css-loader.

My bad, I didn't notice I was using an old less version. That was the culprit. Just updated it to 2.7.2 and the problem is gone.

Uncaught ReferenceError: require is not defined react + webpack

I have been working on a project for about 2 months and used webpack-dev-middleware.
According to the WDM documentation, its just a wrapper for webpack and run the project in the memory to enable hot reloading.
But now when im trying to build and deploy with webpack and same webpack.config.js i get Uncaught ReferenceError: require is not defined error.
I have searched alot and couldn't find a right answer for my case.
I'd really appreciate any help :).
my webpack.config.js
var ExtractTextPlugin = require('extract-text-webpack-plugin');
var path = require('path');
var autoprefixer = require('autoprefixer');
const webpack = require('webpack');
var fs = require('fs')
module.exports = {
entry: './src/client.js',
output: {
path: path.join(__dirname, 'public'),
filename: 'bundle.js'
},
target: 'web',
// keep node_module paths out of the bundle
externals: fs.readdirSync(path.resolve(__dirname, 'node_modules')).concat([
'react-dom/server', 'react/addons',
]).reduce(function (ext, mod) {
ext[mod] = 'commonjs ' + mod
return ext
}, {}),
node: {
__filename: true,
__dirname: true
},
plugins: [
new ExtractTextPlugin('styles.css'),
],
module: {
loaders: [
{
test: /\.js$/,
loader: 'babel-loader',
}, {
test: /\.(png|jpg|jpeg|gif|svg|woff|woff2)$/,
loader: 'url-loader?limit=100000&name=/[hash].[ext]',
}, {
test: /\.scss$/,
loader: ExtractTextPlugin.extract(['css-loader', 'sass-loader']),
},
{ test: /\.json$/, loader: "json-loader"}
],
},
devtool: 'cheap-module-source-map'
}
I'm using webpack version : 1.13.3 as local.

In my case reason was:
...
module: {
noParse: /\.min\.js$/,
...
I've commented it out

Webpack loads from the wrong URL when the path changes

I'm writing a react app and everything works fine when I navigate to localhost:3000, but when I try to go to localhost:3000/foo/page, I get an error message that tells me localhost:3000/foo/bundle.js cannot be loaded.
To me, this looks like a problem with Webpack looking in the wrong place for bundle.js, but I'm not sure. How do I get the app to always look at localhost:3000 for bundle.js?
This is some of my webpack config.
var TARGET = process.env.npm_lifecycle_event;
var ROOT_PATH = path.resolve(__dirname);
var APP_PATH = path.resolve(ROOT_PATH, 'app');
var BUILD_PATH = path.resolve(ROOT_PATH, 'dist');
process.env.BABEL_ENV = TARGET;
var common = {
entry: APP_PATH,
output: {
path: BUILD_PATH,
filename: 'bundle.js'
},
module: {
loaders: [
{
test: /\.jsx?$/,
loaders: ['babel'],
include: APP_PATH
},
{
test: /\.svg$/,
loader: 'url-loader?limit=8192',
include: APP_PATH
},
{
test: /\.png$/,
loader: 'url-loader?limit=8192',
include: APP_PATH
},
{
test: /\.ico$/,
loader: 'url-loader?limit=8192',
include: APP_PATH
}
]
},
plugins: [
new HtmlWebpackPlugin({
title: 'foobar',
template: path.resolve(APP_PATH, 'index.html'),
favicon: path.resolve(APP_PATH, 'images', 'favicon.ico')
})
]
};
if (TARGET === 'start' || !TARGET) {
module.exports = merge(common, {
devtool: 'eval-source-map',
module: {
loaders: [
{
test: /\.scss$/,
loaders: ['style', 'css', 'sass'],
include: APP_PATH
}
]
},
devServer: {
historyApiFallback: true,
hot: true,
inline: true,
port: 3000,
progress: true
},
plugins: [
new webpack.HotModuleReplacementPlugin()
]
});
}

Add output.publicPath: '/' to your webpack config.
output: {
path: BUILD_PATH,
publicPath: '/',
filename: 'bundle.js'
}
HtmlWebpackPlugin most probably generates the file which have:
<script src="bundle.js"></script>
Setting up output.publicPath: '/' will make it:
<script src="/bundle.js"></script>
From Webpack Config page:
output.publicPath
The publicPath specifies the public URL address of
the output files when referenced in a browser. For loaders that embed
or tags or reference assets like images, publicPath is
used as the href or url() to the file when it’s different then their
location on disk (as specified by path). This can be helpful when you
want to host some or all output files on a different domain or on a
CDN. The Webpack Dev Server also takes a hint from publicPath using it
to determine where to serve the output files from. As with path you
can use the [hash] substitution for a better caching profile.