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Vue 3 - How to add Polyfills to ChainWebpack

Using Vue 3, how do I add path-browserify to vue.config.js?
module.exports = {
chainWebpack: config => {}
}
I am receiving the following error when compiling:
BREAKING CHANGE: webpack < 5 used to include polyfills for node.js core modules by default.
This is no longer the case. Verify if you need this module and configure a polyfill for it.
If you want to include a polyfill, you need to:
- add a fallback 'resolve.fallback: { "path": require.resolve("path-browserify") }'
- install 'path-browserify'
If you don't want to include a polyfill, you can use an empty module like this:
resolve.fallback: { "path": false }

Webpack 5 removed some things that Webpack 4 included in the bundle.
To get it all back in a vue3 app you can use the polyfill plugin.
From a vanilla create-vue-app with babel:
> npm i node-polyfill-webpack-plugin
babel.config.js
module.exports = {
presets: [
'#vue/cli-plugin-babel/preset'
]
}
vue.config.js
const { defineConfig } = require("#vue/cli-service");
const NodePolyfillPlugin = require("node-polyfill-webpack-plugin");
module.exports = defineConfig({
transpileDependencies: true,
configureWebpack: {
plugins: [new NodePolyfillPlugin()],
optimization: {
splitChunks: {
chunks: "all",
},
},
},
});

With #Zack's help, using chainWebpack:
const NodePolyfillPlugin = require('node-polyfill-webpack-plugin')
module.exports = {
chainWebpack: config => {
config.plugin('polyfills').use(NodePolyfillPlugin)
},
}

Rollup is not generating typescript sourcemap

I am using rollup with svelte + typescript + scss. My problem is that I am not able to generate source maps.
Following is my rollup config file:
import svelte from 'rollup-plugin-svelte'
import resolve from '#rollup/plugin-node-resolve'
import commonjs from '#rollup/plugin-commonjs'
import livereload from 'rollup-plugin-livereload'
import { terser } from 'rollup-plugin-terser'
import typescript from '#rollup/plugin-typescript'
import alias from '#rollup/plugin-alias'
const production = !process.env.ROLLUP_WATCH
const path = require('path').resolve(__dirname, 'src')
const svelteOptions = require('./svelte.config')
function serve() {
let server
function toExit() {
if (server) server.kill(0)
}
return {
writeBundle() {
if (server) return
server = require('child_process').spawn(
'yarn',
['run', 'start', '--', '--dev'],
{
stdio: ['ignore', 'inherit', 'inherit'],
shell: true,
}
)
process.on('SIGTERM', toExit)
process.on('exit', toExit)
},
}
}
export default {
input: 'src/main.ts',
output: {
sourcemap: true,
format: 'iife',
name: 'app',
file: 'public/build/bundle.js',
},
plugins: [
alias({
entries: [
{ find: '#app', replacement: `${path}` },
{ find: '#components', replacement: `${path}/components` },
{ find: '#includes', replacement: `${path}/includes` },
{ find: '#styles', replacement: `${path}/styles` },
{ find: '#pages', replacement: `${path}/pages` },
],
}),
svelte(svelteOptions),
// If you have external dependencies installed from
// npm, you'll most likely need these plugins. In
// some cases you'll need additional configuration -
// consult the documentation for details:
// https://github.com/rollup/plugins/tree/master/packages/commonjs
resolve({
browser: true,
dedupe: ['svelte'],
}),
commonjs(),
typescript({ sourceMap: !production }),
// In dev mode, call `npm run start` once
// the bundle has been generated
!production && serve(),
// Watch the `public` directory and refresh the
// browser on changes when not in production
!production && livereload('public'),
// If we're building for production (npm run build
// instead of npm run dev), minify
production && terser(),
],
watch: {
clearScreen: false,
},
}
I am not sure what exactly am I doing wrong. Here is the link to code I am using.
Any help will be deeply appreciated!

This is what worked for me: you need to set sourceMap: false in the typescript rollup plugin options.
export default {
input: 'src/main.ts',
output: {
sourcemap: true,
format: 'iife',
...
},
plugins: [
...
svelte(...),
typescript({ sourceMap: false }),
...
]
}
It turns out rollup's sourcemap collapser conflicts with the typescript's plugin sourcemap generator. That's why it works on prod builds but not in dev builds (because originally it is sourceMap: !production). Just let rollup do the heavy lifting.

As also mentioned by others, it seems like the combination of TypeScript and Rollup leads to the problem. Disabling the source map in TypeScript only fixes the problem of mapping Svelte to TypeScript. However you only receive a source map showing source in the compiled JavaScript, not in the original TypeScript. I finally found a solution, that worked for me: Just add the Option inlineSources: true to the TypeScript options:
typescript({ sourceMap: !production, inlineSources: !production }),
This circumvents the problem by simply not creating a duplicate SourceMap, but by copying the source code from TypeScript into the SourceMap.

For anyone using terser, not svelte, this solved the same problem for me:
import sourcemaps from 'rollup-plugin-sourcemaps';
import { terser } from 'rollup-plugin-terser';
import typescript from '#rollup/plugin-typescript';
export default [
{
input: 'dist/index.js',
output: [
{
file: 'dist/cjs/index.js',
format: 'cjs'
},
{
file: 'dist/fesm2015/index.js',
format: 'es'
}
],
plugins: [
sourcemaps(),
terser(),
typescript({ sourceMap: true, inlineSources: true })
]
}
];
Apparently rollup-plugin-sourcemaps is needed to do the magic necessary to utilize the map files generated by the TypeScript compiler and feed them to terser.

For me, I am able to map, by making sourcemap: "inline"
In the /build/index.esm.js file will have mapping inside.
export default {
input: "src/index.ts",
output: [
{
file: 'build/index.esm.js',
format: 'es',
sourcemap: "inline"
},
],
plugins: [
typescript({ sourceMap: false, inlineSources: true }),
]
}

I was having a similar issue with Karma, rollup, and typescript. I fixed it by adding "sourceRoot":"/base/" to my tsconfig.json file.
Before: map file entries pointed to /src/.
After: map file entries pointed to /base/src/ and everything worked.
// tsconfig.rollup.json
"compilerOptions": {
"module": "ES2022",
"esModuleInterop": true,
"target": "ES2022",
"moduleResolution": "classic",
"sourceMap": true,
"sourceRoot": "/base/"
...
}
// rollup.config.js
import typescript from '#rollup/plugin-typescript';
export default [
{
input: './src/test/test_context.spec.ts',
output: {
file: './dist/test/test_context.spec.js',
format: 'es',
sourcemap: 'inline'
},
plugins: [
typescript({
tsconfig: './tsconfig.rollup.json'
})
]
}
];

Webpack - module not found even though module exists

This is a branch off of my previous question and applied suggestions. But I am still having major issues.
I now have my babel transpiler, along with a .babelrc file in place. My import code to import my module looks like this:
var init = require('./app/js/modules/toc');
init();
However I'm getting this:
ERROR in ./app/js/script.js
Module not found: Error: Cannot resolve 'file' or 'directory' ./app/js/modules/toc in /projects/project-root/app/js
# ./app/js/script.js 1:11-42
Webpack config:
var debug = process.env.NODE_ENV !== "production";
var webpack = require('webpack');
module.exports = {
context: __dirname,
devtool: debug ? "inline-sourcemap" : null,
entry: "./app/js/script.js",
module: {
rules: [{
test: /\.js$/,
use: 'babel-loader'
}]
},
output: {
path: __dirname + "public/javascripts",
filename: "scripts.min.js"
},
plugins: debug ? [] : [
new webpack.optimize.DedupePlugin(),
new webpack.optimize.OccurenceOrderPlugin(),
new webpack.optimize.UglifyJsPlugin({ mangle: false, sourcemap: false }),
],
};
.babelrc
{
"presets": ["es2015"]
}
Gulptask
//scripts task, also "Uglifies" JS
gulp.task('scripts', function() {
gulp.src('app/js/script.js')
.pipe(webpack(require('./webpack.config.js')))
.pipe(gulp.dest('public/javascripts'))
.pipe(livereload());
});
I'm totally lost...what am I doing wrong?
For my import code I also tried:
import {toc} from './modules/toc'
toc();
UPDATE: As recommended I needed to add resolve to my config. It looks like this now:
var debug = process.env.NODE_ENV !== "production";
var webpack = require('webpack');
module.exports = {
context: __dirname,
devtool: debug ? "inline-sourcemap" : null,
entry: "./app/js/script.js",
resolve: {
extensions: ['.js']
},
module: {
rules: [{
test: /\.js$/,
use: 'babel-loader'
}]
},
output: {
path: __dirname + "public/javascripts",
filename: "scripts.min.js"
},
plugins: debug ? [] : [
new webpack.optimize.DedupePlugin(),
new webpack.optimize.OccurenceOrderPlugin(),
new webpack.optimize.UglifyJsPlugin({ mangle: false, sourcemap: false }),
],
};
Sadly I still get:
ERROR in Entry module not found: Error: Cannot resolve 'file' or
'directory' ./app/js/script.js in /projects/project-root
Does my file structure need to change?

Whenever you import/require a module without specifying a file extension, you need to tell webpack how to resolve it. This is done by the resolve section inside the webpack config.
resolve: {
extensions: ['.js'] // add your other extensions here
}
As a rule of thumb: whenever webpack complains about not resolving a module, the answer probably lies in the resolve config.
Let me know about any further questions and if this works.
EDIT
resolve directly to the root level of your config:
// webpack.config.js
module.export = {
entry: '...',
// ...
resolve: {
extensions: ['.js']
}
// ...
};

You are specifying an entry point in your webpack config AND in gulp. Remove the entry property in your webpack config.
If you specify it twice, the gulp config will tell webpack to get the file in ./app/js/script.jsand then webpack in ./app/js/script.js which will result in a path like ./app/js/app/js/script.js.
Keep us posted if you fixed it. =)

Given that your script is located at ./app/js/script.js and the requested module is there ./app/js/modules/toc, you would need to call it relatively to your script => ./modules/toc should work.
This is because both your script and module are located in the jsfolder.

Build error while compiling create-react-app

I am new to Reactjs and am started learning it. I have been trying to start a basic hello world program but its failing at compilation level.
Created a start up hello-word program with create-react-app hello-world it gave me a nice folder structure with bunch of files.
And Here you can see the compilation error
Failed to compile
./src/index.js
Module build failed: Error: Failed to load plugin import: Cannot find module
'eslint-plugin-import'
Referenced from:
at Array.forEach (native)
at Array.reduceRight (native)
This error occurred during the build time and cannot be dismissed.
Here the error states cannot find module so i tried to install eslint plugin import ,standard ..etc but still its not worked.
Below is my webpack.config.dev.js
// #remove-on-eject-begin
/**
* Copyright (c) 2015-present, Facebook, Inc.
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of this source tree.
*/
// #remove-on-eject-end
'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');
const env = getClientEnvironment(publicUrl);
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',
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: {
// Next line is not used in dev but WebpackDevServer crashes without it:
path: paths.appBuild,
// 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: {
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)
),
extensions: ['.web.js', '.js', '.json', '.web.jsx', '.jsx'],
alias: {
// #remove-on-eject-begin
// Resolve Babel runtime relative to react-scripts.
// It usually still works on npm 3 without this but it would be
// unfortunate to rely on, as react-scripts could be symlinked,
// and thus babel-runtime might not be resolvable from the source.
'babel-runtime': path.dirname(
require.resolve('babel-runtime/package.json')
),
// #remove-on-eject-end
// 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/).
new ModuleScopePlugin(paths.appSrc, [paths.appPackageJson]),
],
},
module: {
strictExportPresence: true,
rules: [
// TODO: Disable require.ensure as it's not a standard language feature.
// We are waiting for https://github.com/facebookincubator/create-react-
app/issues/2176.
// { parser: { requireEnsure: false } },
// First, run the linter.
// It's important to do this before Babel processes the JS.
{
test: /\.(js|jsx)$/,
enforce: 'pre',
use: [
{
options: {
formatter: eslintFormatter,
eslintPath: require.resolve('eslint'),
// #remove-on-eject-begin
baseConfig: {
extends: [require.resolve('eslint-config-react-app')],
},
ignore: false,
useEslintrc: false,
// #remove-on-eject-end
},
loader: require.resolve('eslint-loader'),
},
],
include: paths.appSrc,
},
{
// "oneOf" will traverse all following loaders until one will
// match the requirements. When no loader matches it will fall
// back to the "file" loader at the end of the loader list.
oneOf: [
{
test: [/\.bmp$/, /\.gif$/, /\.jpe?g$/, /\.png$/],
loader: require.resolve('url-loader'),
options: {
limit: 10000,
name: 'static/media/[name].[hash:8].[ext]',
},
},
// Process JS with Babel.
{
test: /\.(js|jsx)$/,
include: paths.appSrc,
loader: require.resolve('babel-loader'),
options: {
// #remove-on-eject-begin
babelrc: false,
presets: [require.resolve('babel-preset-react-app')],
cacheDirectory: 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.
{
test: /\.css$/,
use: [
require.resolve('style-loader'),
{
loader: require.resolve('css-loader'),
options: {
importLoaders: 1,
},
},
{
loader: require.resolve('postcss-loader'),
options: {
// Necessary for external CSS imports to work
ident: 'postcss',
plugins: () => [
require('postcss-flexbugs-fixes'),
autoprefixer({
browsers: [
'>1%',
'last 4 versions',
'Firefox ESR',
'not ie < 9', // React doesn't support IE8 anyway
],
flexbox: 'no-2009',
}),
],
},
},
],
},
{
// Exclude `js` files to keep "css" loader working as it injects
// it's runtime that would otherwise processed through "file"
loader.
// Also exclude `html` and `json` extensions so they get processed
// by webpacks internal loaders.
exclude: [/\.js$/, /\.html$/, /\.json$/],
loader: require.resolve('file-loader'),
options: {
name: 'static/media/[name].[hash:8].[ext]',
},
},
],
},
],
},
plugins: [
new InterpolateHtmlPlugin(env.raw),
// Generates an `index.html` file with the <script> injected.
new HtmlWebpackPlugin({
inject: true,
template: paths.appHtml,
}),
new webpack.NamedModulesPlugin(),
new webpack.DefinePlugin(env.stringified),
new webpack.HotModuleReplacementPlugin(),
new CaseSensitivePathsPlugin(),
new WatchMissingNodeModulesPlugin(paths.appNodeModules),
new webpack.IgnorePlugin(/^\.\/locale$/, /moment$/),
],
node: {
dgram: 'empty',
fs: 'empty',
net: 'empty',
tls: 'empty',
child_process: 'empty',
},
performance: {
hints: false,
},
};
Can any one guide me how to come out of this build error.

This means eslint-plugin-import not available in your node_modules.
A fresh npm install eslint-plugin-import and restart the application should fix this issue.
If that didn't fix, try upgrading your npm version:
npm install -g npm#latest

Finally issue got resolved after installing few below packages globally:
eslint-config-react-app
eslint
babel-eslint
eslint-plugin-react
eslint-plugin-import
eslint-plugin-jsx-a11y
eslint-plugin-flowtype
And deleted package.lock.json file then ran npm install
Finally npm start Its just worked. Thank you

Run this command:
"lint:fix": "eslint './src/**/*.{js,jsx}' --fix"
Then fixed all problems.
And Sure file ".eslint.js" has no any problem:
module.exports = {
root: true,
env: {
browser: true,
node: true,
},
parserOptions: {
parser: "babel-eslint",
ecmaVersion: 2020,
sourceType: "module",
},
extends: ["plugin:react/recommended", "plugin:prettier/recommended"],
plugins: [],
rules: {
"react/prop-types": 0,
},
};

Passing environment-dependent variables in webpack

I'm trying to convert an angular app from gulp to webpack. in gulp I use gulp-preprocess to replace some variables in the html page (e.g. database name) depending on the NODE_ENV. What is the best way of achieving a similar result with webpack?

There are two basic ways to achieve this.
DefinePlugin
new webpack.DefinePlugin({
'process.env.NODE_ENV': JSON.stringify(process.env.NODE_ENV || 'development')
}),
Note that this will just replace the matches "as is". That's why the string is in the format it is. You could have a more complex structure, such as an object there but you get the idea.
EnvironmentPlugin
new webpack.EnvironmentPlugin(['NODE_ENV'])
EnvironmentPlugin uses DefinePlugin internally and maps the environment values to code through it. Terser syntax.
Alias
Alternatively you could consume configuration through an aliased module. From consumer side it would look like this:
var config = require('config');
Configuration itself could look like this:
resolve: {
alias: {
config: path.join(__dirname, 'config', process.env.NODE_ENV)
}
}
Let's say process.env.NODE_ENV is development. It would map into ./config/development.js then. The module it maps to can export configuration like this:
module.exports = {
testing: 'something',
...
};

Just another option, if you want to use only a cli interface, just use the define option of webpack. I add the following script in my package.json :
"build-production": "webpack -p --define process.env.NODE_ENV='\"production\"' --progress --colors"
So I just have to run npm run build-production.

I investigated a couple of options on how to set environment-specific variables and ended up with this:
I have 2 webpack configs currently:
webpack.production.config.js
new webpack.DefinePlugin({
'process.env':{
'NODE_ENV': JSON.stringify('production'),
'API_URL': JSON.stringify('http://localhost:8080/bands')
}
}),
webpack.config.js
new webpack.DefinePlugin({
'process.env':{
'NODE_ENV': JSON.stringify('development'),
'API_URL': JSON.stringify('http://10.10.10.10:8080/bands')
}
}),
In my code I get the value of API_URL in this (brief) way:
const apiUrl = process.env.API_URL;
EDIT 3rd of Nov, 2016
Webpack docs has an example: https://webpack.js.org/plugins/define-plugin/#usage
new webpack.DefinePlugin({
PRODUCTION: JSON.stringify(true),
VERSION: JSON.stringify("5fa3b9"),
BROWSER_SUPPORTS_HTML5: true,
TWO: "1+1",
"typeof window": JSON.stringify("object")
})
With ESLint you need to specifically allow undefined variables in code, if you have no-undef rule on. http://eslint.org/docs/rules/no-undef like this:
/*global TWO*/
console.log('Running App version ' + TWO);
EDIT 7th of Sep, 2017 (Create-React-App specific)
If you're not into configuring too much, check out Create-React-App: Create-React-App - Adding Custom Environment Variables. Under the hood CRA uses Webpack anyway.

You can pass environment variables without additional plugins using --env
Webpack 2-4
webpack --config webpack.config.js --env.foo=bar
Webpack 5+ (without.)
webpack --config webpack.config.js --env foo=bar
Then, use the variable in webpack.config.js:
module.exports = function(env) {
if (env.foo === 'bar') {
// do something
}
}
Further Reading: Webpack 2.0 doesn't support custom command line arguments?
#2254

You can directly use the EnvironmentPlugin available in webpack to have access to any environment variable during the transpilation.
You just have to declare the plugin in your webpack.config.js file:
var webpack = require('webpack');
module.exports = {
/* ... */
plugins: [
new webpack.EnvironmentPlugin(['NODE_ENV'])
]
};
Note that you must declare explicitly the name of the environment variables you want to use.

To add to the bunch of answers personally I prefer the following:
const webpack = require('webpack');
const prod = process.argv.indexOf('-p') !== -1;
module.exports = {
...
plugins: [
new webpack.DefinePlugin({
process: {
env: {
NODE_ENV: prod? `"production"`: '"development"'
}
}
}),
...
]
};
Using this there is no funky env variable or cross-platform problems (with env vars). All you do is run the normal webpack or webpack -p for dev or production respectively.
Reference: Github issue

Since my Edit on the above post by thevangelist wasn't approved, posting additional information.
If you want to pick value from package.json like a defined version number and access it through DefinePlugin inside Javascript.
{"version": "0.0.1"}
Then, Import package.json inside respective webpack.config, access the attribute using the import variable, then use the attribute in the DefinePlugin.
const PACKAGE = require('../package.json');
const _version = PACKAGE.version;//Picks the version number from package.json
For example certain configuration on webpack.config is using METADATA for DefinePlugin:
const METADATA = webpackMerge(commonConfig({env: ENV}).metadata, {
host: HOST,
port: PORT,
ENV: ENV,
HMR: HMR,
RELEASE_VERSION:_version//Version attribute retrieved from package.json
});
new DefinePlugin({
'ENV': JSON.stringify(METADATA.ENV),
'HMR': METADATA.HMR,
'process.env': {
'ENV': JSON.stringify(METADATA.ENV),
'NODE_ENV': JSON.stringify(METADATA.ENV),
'HMR': METADATA.HMR,
'VERSION': JSON.stringify(METADATA.RELEASE_VERSION)//Setting it for the Scripts usage.
}
}),
Access this inside any typescript file:
this.versionNumber = process.env.VERSION;
The smartest way would be like this:
// webpack.config.js
plugins: [
new webpack.DefinePlugin({
VERSION: JSON.stringify(require("./package.json").version)
})
]
Thanks to Ross Allen

Just another answer that is similar to #zer0chain's answer. However, with one distinction.
Setting webpack -p is sufficient.
It is the same as:
--define process.env.NODE_ENV="production"
And this is the same as
// webpack.config.js
const webpack = require('webpack');
module.exports = {
//...
plugins:[
new webpack.DefinePlugin({
'process.env.NODE_ENV': JSON.stringify('production')
})
]
};
So you may only need something like this in package.json Node file:
{
"name": "projectname",
"version": "1.0.0",
"description": "",
"main": "index.js",
"scripts": {
"test": "echo \"Error: no test specified\" && exit 1",
"debug": "webpack -d",
"production": "webpack -p"
},
"author": "prosti",
"license": "ISC",
"dependencies": {
"webpack": "^2.2.1",
...
}
}
Just a few tips from the DefinePlugin:
The DefinePlugin allows you to create global constants which can be configured at compile time. This can be useful for allowing different behavior between development builds and release builds. For example, you might use a global constant to determine whether logging takes place; perhaps you perform logging in your development build but not in the release build. That's the sort of scenario the DefinePlugin facilitates.
That this is so you can check if you type webpack --help
Config options:
--config Path to the config file
[string] [default: webpack.config.js or webpackfile.js]
--env Enviroment passed to the config, when it is a function
Basic options:
--context The root directory for resolving entry point and stats
[string] [default: The current directory]
--entry The entry point [string]
--watch, -w Watch the filesystem for changes [boolean]
--debug Switch loaders to debug mode [boolean]
--devtool Enable devtool for better debugging experience (Example:
--devtool eval-cheap-module-source-map) [string]
-d shortcut for --debug --devtool eval-cheap-module-source-map
--output-pathinfo [boolean]
-p shortcut for --optimize-minimize --define
process.env.NODE_ENV="production"
[boolean]
--progress Print compilation progress in percentage [boolean]

I found the following solution to be easiest to setup environment variable for Webpack 2:
For example we have a webpack settings:
var webpack = require('webpack')
let webpackConfig = (env) => { // Passing envirmonment through
// function is important here
return {
entry: {
// entries
},
output: {
// outputs
},
plugins: [
// plugins
],
module: {
// modules
},
resolve: {
// resolves
}
}
};
module.exports = webpackConfig;
Add Environment Variable in Webpack:
plugins: [
new webpack.EnvironmentPlugin({
NODE_ENV: 'development',
}),
]
Define Plugin Variable and add it to plugins:
new webpack.DefinePlugin({
'NODE_ENV': JSON.stringify(env.NODE_ENV || 'development')
}),
Now when running webpack command, pass env.NODE_ENV as argument:
webpack --env.NODE_ENV=development
// OR
webpack --env.NODE_ENV development
Now you can access NODE_ENV variable anywhere in your code.

I prefer using .env file for different environment.
Use webpack.dev.config to copy env.dev to .env into root folder
Use webpack.prod.config to copy env.prod to .env
and in code
use
require('dotenv').config();
const API = process.env.API ## which will store the value from .env file

My workaround for the webpack version "webpack": "^4.29.6" is very simple.
//package.json
{
...
"scripts": {
"build": "webpack --mode production",
"start": "webpack-dev-server --open --mode development"
},
}
you can pass --mode parameter with your webpack commnad then in webpack.config.js
// webpack.config.json
module.exports = (env,argv) => {
return {
...
externals: {
// global app config object
config: JSON.stringify({
apiUrl: (argv.mode==="production") ? '/api' : 'localhost:3002/api'
})
}
}
And I use baseurl in my code like this
// my api service
import config from 'config';
console.log(config.apiUrl) // like fetch(`${config.apiUrl}/users/user-login`)

To add to the bunch of answers:
Use ExtendedDefinePlugin instead of DefinePlugin
npm install extended-define-webpack-plugin --save-dev.
ExtendedDefinePlugin is much simpler to use and is documented :-)
link
Because DefinePlugin lacks good documentation, I want to help out, by saying that it actually works like #DEFINE in c#.
#if (DEBUG)
Console.WriteLine("Debugging is enabled.");
#endif
Thus, if you want to understand how DefinePlugin works, read the c# #define doucmentation. link

Since Webpack v4, simply setting mode in your Webpack config will set the NODE_ENV for you (via DefinePlugin). Docs here.

Here is a way that has worked for me and has allowed me keep my environment variables DRY by reusing a json file.
const webpack = require('webpack');
let config = require('./settings.json');
if (__PROD__) {
config = require('./settings-prod.json');
}
const envVars = {};
Object.keys(config).forEach((key) => {
envVars[key] = JSON.stringify(config[key]);
});
new webpack.DefinePlugin({
'process.env': envVars
}),

dotenv-webpack
A secure webpack plugin that supports dotenv and other environment variables and only exposes what you choose and use.
with some workaround with configuration based on defaults option to achieve that, once the package has .env.defaults file to as initial values for env variables you can use it for development and let .env for your production.
Usage
install the package
npm install dotenv-webpack --save-dev
Create a .env.defaults file
API_URL='dev_url/api/'
create a .env file leave it empty, let defaults works, update it on your deploy process
config webpack - webpack.config.js
new Dotenv({
defaults: true
})
dev environement test file.js
console.log(process.env.API_URL)
// Outputs: dev_url/api/
on build, update empty .env file
API_URL='prod_url/api/'
dotenv-webpack will use this to and override env.defaults
prod environement test file.js
console.log(process.env.API_URL)
// Outputs: prod_url/api/
dotenv-webpack
dotenv-defaults

I'm not a huge fan of...
new webpack.DefinePlugin({
'process.env': envVars
}),
...as it does not provides any type of security. instead, you end up boosting your secret stuff, unless you add a webpack to gitignore 🤷‍♀️ there is a better solution.
Basically with this config once you compile your code all the process env variables will be removed from the entire code, there is not going to be a single process.env.VAR up thanks to the babel plugin transform-inline-environment-variables
PS if you do not want to end up with a whole bunch of undefines, make sure you call the env.js before webpack calls babel-loader, that's why it is the first thing webpack calls. the array of vars in babel.config.js file must match the object on env.js. now there is only one mow thing to do.
add a .env file put all your env variables there, the file must be at the root of the project or feel free to add it where ever u want, just make sure to set the same location on the env.js file and also add it to gitignore
const dotFiles = ['.env'].filter(Boolean);
if (existsSync(dotFiles)) {
require("dotenv-expand")(require("dotenv").config((dotFiles)));
}
If you want to see the whole babel + webpack + ts get it from heaw
https://github.com/EnetoJara/Node-typescript-babel-webpack.git
and same logic applies to react and all the other 💩
config
---webpack.js
---env.js
src
---source code world
.env
bunch of dotFiles
env.js
"use strict";
/***
I took the main idea from CRA, but mine is more cooler xD
*/
const {realpathSync, existsSync} = require('fs');
const {resolve, isAbsolute, delimiter} = require('path');
const NODE_ENV = process.env.NODE_ENV || "development";
const appDirectory = realpathSync(process.cwd());
if (typeof NODE_ENV !== "string") {
throw new Error("falle and stuff");
}
const dotFiles = ['.env'].filter(Boolean);
if (existsSync(dotFiles)) {
require("dotenv-expand")(require("dotenv").config((dotFiles)));
}
process.env.NODE_PATH = (process.env.NODE_PATH || "")
.split(delimiter)
.filter(folder => folder && isAbsolute(folder))
.map(folder => resolve(appDirectory, folder))
.join(delimiter);
const ENETO_APP = /^ENETO_APP_/i;
module.exports = (function () {
const raw = Object.keys ( process.env )
.filter ( key => ENETO_APP.test ( key ) )
.reduce ( ( env, key ) => {
env[ key ] = process.env[ key ];
return env;
},
{
BABEL_ENV: process.env.ENETO_APP_BABEL_ENV,
ENETO_APP_DB_NAME: process.env.ENETO_APP_DB_NAME,
ENETO_APP_DB_PASSWORD: process.env.ENETO_APP_DB_PASSWORD,
ENETO_APP_DB_USER: process.env.ENETO_APP_DB_USER,
GENERATE_SOURCEMAP: process.env.ENETO_APP_GENERATE_SOURCEMAP,
NODE_ENV: process.env.ENETO_APP_NODE_ENV,
PORT: process.env.ENETO_APP_PORT,
PUBLIC_URL: "/"
} );
const stringyField = {
"process.env": Object.keys(raw).reduce((env, key)=> {
env[key]=JSON.stringify(raw[key]);
return env;
},{}),
};
return {
raw, stringyField
}
})();
webpack file with no plugins troll
"use strict";
require("core-js");
require("./env.js");
const path = require("path");
const nodeExternals = require("webpack-node-externals");
module.exports = env => {
return {
devtool: "source-map",
entry: path.join(__dirname, '../src/dev.ts'),
externals: [nodeExternals()],
module: {
rules: [
{
exclude: /node_modules/,
test: /\.ts$/,
use: [
{
loader: "babel-loader",
},
{
loader: "ts-loader"
}
],
},
{
test: /\.(png|jpg|gif)$/,
use: [
{
loader: "file-loader",
},
],
},
],
},
node: {
__dirname: false,
__filename: false,
},
optimization: {
splitChunks: {
automaticNameDelimiter: "_",
cacheGroups: {
vendor: {
chunks: "initial",
minChunks: 2,
name: "vendor",
test: /[\\/]node_modules[\\/]/,
},
},
},
},
output: {
chunkFilename: "main.chunk.js",
filename: "name-bundle.js",
libraryTarget: "commonjs2",
},
plugins: [],
resolve: {
extensions: ['.ts', '.js']
} ,
target: "node"
};
};
babel.config.js
module.exports = api => {
api.cache(() => process.env.NODE_ENV);
return {
plugins: [
["#babel/plugin-proposal-decorators", { legacy: true }],
["#babel/plugin-transform-classes", {loose: true}],
["#babel/plugin-external-helpers"],
["#babel/plugin-transform-runtime"],
["#babel/plugin-transform-modules-commonjs"],
["transform-member-expression-literals"],
["transform-property-literals"],
["#babel/plugin-transform-reserved-words"],
["#babel/plugin-transform-property-mutators"],
["#babel/plugin-transform-arrow-functions"],
["#babel/plugin-transform-block-scoped-functions"],
[
"#babel/plugin-transform-async-to-generator",
{
method: "coroutine",
module: "bluebird",
},
],
["#babel/plugin-proposal-async-generator-functions"],
["#babel/plugin-transform-block-scoping"],
["#babel/plugin-transform-computed-properties"],
["#babel/plugin-transform-destructuring"],
["#babel/plugin-transform-duplicate-keys"],
["#babel/plugin-transform-for-of"],
["#babel/plugin-transform-function-name"],
["#babel/plugin-transform-literals"],
["#babel/plugin-transform-object-super"],
["#babel/plugin-transform-shorthand-properties"],
["#babel/plugin-transform-spread"],
["#babel/plugin-transform-template-literals"],
["#babel/plugin-transform-exponentiation-operator"],
["#babel/plugin-proposal-object-rest-spread"],
["#babel/plugin-proposal-do-expressions"],
["#babel/plugin-proposal-export-default-from"],
["#babel/plugin-proposal-export-namespace-from"],
["#babel/plugin-proposal-logical-assignment-operators"],
["#babel/plugin-proposal-throw-expressions"],
[
"transform-inline-environment-variables",
{
include: [
"ENETO_APP_PORT",
"ENETO_APP_NODE_ENV",
"ENETO_APP_BABEL_ENV",
"ENETO_APP_DB_NAME",
"ENETO_APP_DB_USER",
"ENETO_APP_DB_PASSWORD",
],
},
],
],
presets: [["#babel/preset-env",{
targets: {
node: "current",
esmodules: true
},
useBuiltIns: 'entry',
corejs: 2,
modules: "cjs"
}],"#babel/preset-typescript"],
};
};

now 2020, i am face to same question, but for this old question, there are so many new answer, just list some of it:
this is webpack.config.js
plugins: [
new HtmlWebpackPlugin({
// 1. title is the parameter, you can use in ejs template
templateParameters:{
title: JSON.stringify(someting: 'something'),
},
}),
//2. BUILT_AT is a parameter too. can use it.
new webpack.DefinePlugin({
BUILT_AT: webpack.DefinePlugin.runtimeValue(Date.now,"some"),
}),
//3. for webpack5, you can use global variable: __webpack_hash__
//new webpack.ExtendedAPIPlugin()
],
//4. this is not variable, this is module, so use 'import tt' to use it.
externals: {
'ex_title': JSON.stringify({
tt: 'eitentitle',
})
},
the 4 ways only basic, there are even more ways that i believe. but i think maybe this 4ways is the most simple.