Develop Reference

Webpack configuration to allow import

I am creating a basic structure where the controller.js would need some Views to be imported from view.js and hence this is what I am using in the controller.js
import View from './View'
However there was an issue with the bundler with webpack and I ended up visiting this page
https://webpack.js.org/loaders/imports-loader/
and below is webpack.config.js.. I've added the lines at the end to the RULES as metioned in the documentation
I ran npm install npm install imports-loader --save-dev
// SOURCE OF TUTORIAL
// https://www.youtube.com/watch?v=MpGLUVbqoYQ&t=1205s
const HtmlWebpackPlugin = require("html-webpack-plugin");
const path = require("path");
module.exports = {
mode: "development",
devtool: false,
entry: {
main: "./src/js/controller.js",
model: "./src/js/model.js",
},
plugins: [
new HtmlWebpackPlugin({
template: "./src/main.html",
}),
],
module: {
rules: [
{
test: /\.scss$/,
use: [
"style-loader", // injects STYLES into DOM
"css-loader", // turns CSS into commonjs
"sass-loader", // turns SASS into CSS
],
},
{
test: /\.html$/,
use: ["html-loader"],
},
{
test: /\.(png|gif|svg|jpe?g)$/,
type: "asset/resource",
},
{
test: require.resolve("./path/to/example.js"),
loader: "imports-loader",
options: {
type: "module",
imports: "default lib myName",
},
},
],
},
};
The last section of the rule is what I have added.. it's a basic copy paste without really understanding what it does and it didn't work.. I am obviously doing somethibg wrong but I could not figure it out even after reading the section at the link above..
Could someone explain how the last section should be configured so that I am able to use import? I've recently created this webpack configuration based on a youtube tutorial so my knowledge on webpack is very basic..
Any help would be appreciated.

webpack v5 SourceMapDevToolPlugin "exclude" option not working

After upgarding to webpack 5, vendor.js file couldn't be excluded from being source-mapped via SourceMapDevToolPlugin.
// webpack.config.ts - removed other config for brevity
import { Configuration } from 'webpack-dev-server';
export default (env) => {
const config: Configuration = {};
config.mode = 'production';
config.entry = './entry.app.js';
config.output = {
path: path.join(__dirname, '/public'),
pathinfo: true,
filename: '[name].[fullhash].js',
chunkFilename: '[name].[fullhash].js',
};
config.devtool = 'source-map';
config.bail = true;
config.plugins = [
new webpack.SourceMapDevToolPlugin({
filename: '[file].map',
exclude: ['vendor.js'],
}),
];
config.optimization = {
minimize: true,
minimizer: [
new TerserPlugin({
parallel: false,
sourceMap: false,
}),
new CssMinimizerPlugin(),
],
moduleIds: 'deterministic',
splitChunks: {
chunks: 'all',
maxInitialRequests: 100,
minSize: 0,
cacheGroups: {
vendor: {
name: 'vendor',
test: /([/\\]node_modules[/\\]|[/\\]dev[/\\]vendor[/\\])/,
chunks: 'all',
},
},
},
};
return config;
}
// entry.app.js - removed some lines for brevity
import './horrible-asset-loader';
import './setup-for-angular';
import { runApp } from './assets/js/app';
runApp();
// horrible-asset-loader.js
// contains a lot of require statements of npm packages saved into our repository under a vendor folder. crazy i know but I don't know why this was done.
require('ng-bs-daterangepicker/dist/ng-bs-daterangepicker.min.js'); // throwing an error when building because webpack is trying to create a source map for it
// Temporary solution to bundle multiple javascript files into one. This will be replaced by ES6 import.
SourceMapDevToolPlugin exclude config i've tried so far:
// from https://webpack.js.org/plugins/source-map-dev-tool-plugin/#exclude-vendor-maps
exclude: ['vendor.js']
//from https://github.com/webpack/webpack/issues/2431
exclude: /vendor.*.*/
exclude: 'vendor'
// just me desperately trying every possible config
exclude: ['vendor']
exclude: /vendor\.[0-9a-zA-Z]\.js/
exclude: 'vendor.js'
exclude: ['vendor.[chunkhash].js']
exclude: ['vendor.[fullhash].js']
The github issue link mentioned about an issue with UglifyJsPlugin but we aren't using that so I ruled it out.
Although if i set config.devtool to false, the SourceDevToolPlugin config works.
Is there something wrong with my config?
UPDATE: I think i got it now. Looks like i just really have to set devtool to false based on this example: https://webpack.js.org/plugins/source-map-dev-tool-plugin/#basic-use-case
I just thought devtool should only be set to false for development mode because of this note:
If you want to use a custom configuration for this plugin in development mode, make sure to disable the default one. I.e. set devtool: false.
Am I right?
UPDATE 1: Yup! looks like I'm right. I should've read the other comments on the github issue: https://github.com/webpack/webpack/issues/2431#issuecomment-245547872
Sorry for wasting anyone's time.

This was a really silly mistake. I misunderstood the docs for the plugin:
https://webpack.js.org/plugins/source-map-dev-tool-plugin/#basic-use-case
Setting devtool to false fixed the issue.

In Webpack v4 with multiple entries, my splitChunks is not optimized, if my two pages includes core-js, they will all get a copy

You can clone my minimum repo https://github.com/rockmandash/webpack-chunks-question
Or see the code below
page1.js
import 'core-js';
console.log('I am page1');
page2.js
import 'core-js';
import 'react';
import 'react-dom';
console.log('I am page2');
My webpack config:
const path = require('path');
const HtmlWebpackPlugin = require('html-webpack-plugin');
const entriesFilePath = [
require.resolve('./src/page1.js'),
require.resolve('./src/page2.js'),
];
const mode = 'development';
const webpackConfig = entriesFilePath.map((entrieFilePath) => {
const fileName = path.basename(entrieFilePath, path.extname(entrieFilePath));
// fileName would be page1 and page2
return {
mode,
devtool: 'cheap-module-source-map',
entry: {
[fileName]: entrieFilePath,
},
output: {
filename: 'static/js/[name].js',
chunkFilename: 'static/js/[name].chunk.js',
},
optimization: {
splitChunks: {
chunks: 'all',
},
},
plugins: [
// Generates an `index.html` file with the <script> injected.
new HtmlWebpackPlugin(
Object.assign(
{},
{
inject: true,
filename: `${fileName}.html`,
},
),
),
].filter(Boolean),
};
});
module.exports = webpackConfig; // I have to export an array, because in the future, I need to do something else.
The generated dist folder looks like this:
dist
/page1.html
/page2.html
/static
/js
/page1.js.map
/vendors~page2.chunk.js.map
/vendors~page1.chunk.js // this includes core-js !!!!
/page1.js
/page2.js
/vendors~page1.chunk.js.map
/vendors~page2.chunk.js // this includes core-js too !!!!
/page2.js.map
You see, the generated two chunks both includes core-js, how can I make my webpack config smart enough to automatically separate core-js or other common vendor files out of the box?

You do not need to import core-js anywhere. Create a .babelrc file.
{
"presets": [
[
"#babel/preset-env",
{
"debug": true,
"useBuiltIns": "usage",
"corejs": 3
}
]
]
}
Instal #babel/core, #babel/polyfill, #babel/preset-env, babel-loader
Add to webpack
const optimization = {
splitChunks: {
cacheGroups: {
vendor: {
test: /[\\/]node_modules[\\/](react|react-dom)[\\/]/,
name: 'vendor',
chunks: 'all',
}
}
}
};
module: {rules: [{
test: /\.js$/,
exclude: /node_modules/,
use: {
loader: 'babel-loader'
}
}
]},
Take a look at my solution, there is a complete code. Use of core-js. He uses only part polyfil when it is needed.
https://github.com/tomik23/webpack-babel-corejs/blob/master/webpack.config.js#L17
And the second solution needed in your code is to use spliChunks
https://github.com/tomik23/photoBlog/blob/master/config/webpack.config.js#L31
P.S. If you import 'core-js' in this way; you download the whole core-js if you use my method then core-js chooses only what is needed and packages are smaller.

Splitting out react components as widgets

I'm trying to create JS widgets from my existing react app. So currently I have an app that looks something like this
-src
- config
- components
- containers
- lib
- assets
- widgets
- widgetOne
- widgetTwo
- components
- widget.js
- index.js
- index.js
- index.html
So, I want directories in the widgets directories to be self contained apps that I can break out into a separate js file and a client can just add the js script into their page in a script tag.
I've come close but still facing a few issues. Also, I wanted to see if someone had experience doing this following a better pattern.
Right now I'm using webpack to do this splitting. I'm just defining /src/widgets/widgetOne/index.js as an entry point and perfectly creates a separate file.
Here is my webpack:
const appConstants = function() {
switch (process.env.NODE_ENV) {
case 'local':
const localConfig = require('./config/local');
return localConfig.config();
case 'development':
const devConfig = require('./config/development');
return devConfig.config();
case 'production':
default:
const prodConfig = require('./config/production');
return prodConfig.config();
}
};
const HtmlWebPackPlugin = require("html-webpack-plugin");
const webpack = require('webpack');
const BundleAnalyzerPlugin = require('webpack-bundle-analyzer').BundleAnalyzerPlugin;
const htmlWebpackPlugin = new HtmlWebPackPlugin({
template: "./src/index.html",
filename: "./index.html",
hash: true
});
let webpackConfig = {
module: {
rules: [
{
test: /\.(js|jsx)$/,
exclude: /node_modules/,
use: {
loader: "babel-loader"
}
},
{
test: /\.css$/,
exclude: [ /assets/, /node_modules/ ],
use: [
{
loader: "style-loader"
},
{
loader: "css-loader",
options: {
modules: true,
importLoaders: 1,
localIdentName: "[name]_[local]_[hash:base64]",
sourceMap: true,
minimize: true
}
}
]
},
{
test: /\.(pdf|jpg|png|gif|svg|ico)$/,
exclude: [/node_modules/],
use: [
{
loader: 'file-loader'
},
]
},
{
test: /\.(woff|woff2|eot|ttf|svg)$/,
exclude: [/node_modules/],
use: {
loader: 'url-loader?limit100000'
}
}
]
},
entry: {
main: [ "#babel/polyfill", "./src/index.js"],
widgetOne: ["./src/widgets/widgetOne/index.js"]
},
output: {
publicPath: appConstants().BASENAME ? JSON.parse(appConstants().BASENAME) : '/'
},
optimization: {
splitChunks: {
chunks: 'all'
}
},
plugins: [
htmlWebpackPlugin,
new webpack.ContextReplacementPlugin(/moment[/\\]locale$/, /en/),
new BundleAnalyzerPlugin({
analyzerMode: 'disabled',
generateStatsFile: true,
statsOptions: { source: false }
}),
new webpack.DefinePlugin({
'process.env': appConstants()
}),
new webpack.EnvironmentPlugin(['NODE_ENV'])
],
devServer: {
historyApiFallback: true,
port: 9090
}
};
module.exports = webpackConfig;
The problem I have now is while I get the widgetOne.js:
1) I end up with a vendor~widgetOne.js file that I also need to include to make the widgetOne app to work.
2) The widgetOne.js also gets added to my index.html file for my main app which I do not want.
Is there a way to configure webpack properly to make this work?

So, this is the solution I came up with that seems to work. I still don't know if this is the best approach but it' the only one I was able to get to work for me.
I decided to build the widgets as a different environment process and and modify the webpack configs based on that environment.
So the package.json I add this line under scritps:
"build-widgets": "cross-env NODE_ENV=plugins webpack --mode development",
And I added this section to the end of my webpack.config.js file:
// Override webpack configs when building plugins
if ( process.env.NODE_ENV === 'plugins') {
webpackConfig.entry = {
widgetOne: [ "#babel/polyfill", "./src/plugins/widgetOne/index.js"]
}
webpackConfig.output = {
publicPath: appConstants().DS_BASENAME ? JSON.parse(appConstants().DS_BASENAME) : '/',
path: __dirname + '/dist/widgets',
library: 'MyApp',
libraryTarget: 'umd',
umdNamedDefine: true
}
}
Alternatively, I could have just added a second webpack.config.js exclusively to deal with my widgets build. In my case I didn't feel the need for it just yet but it's something to be considered for sure, just for the sake of keeping configs separate.

ReactJS test files issue 'cannot find module' because of webpack module resolver

i'm developing an application with react.js. My application is growing up. So i had little trouble with imports. For example i have a component named foo i'm using it in many places.
import foo from '../../components/foo';
import foo from '../components/foo';
import foo from '../../../components/foo';
As you can see its dirty, not good. So i searched to fix it and i found a solution with webpack. Also i read that title (Configure Webpack’s modules resolution to avoid nested imports) in this article
I added this code into my webpack.config.js file
modules: [
'node_modules',
path.resolve(__dirname, 'src')
]
So my resolve object looks like this
export default {
resolve: {
modules: [
'node_modules',
path.resolve(__dirname, 'src')
],
extensions: ['*', '.js', '.jsx', '.json']
},
...
After that i am able to use import my foo component in anywhere like this.
import foo from 'components/foo';
Everything is okay so far. But problem shows up in test files.
When i try to test foo component it says
Cannot find module 'components/foo' from 'foo.js'
Example test file.
foo.spec.js
import React from 'react';
import foo from 'components/foo';
describe('(Component) foo', () => {
it('should render foo', () => {
expect(true).toBe(true);
});
});
Here is the first problem. I can not import foo like this.
Note: My test file is not in src folder it is in the test folder.
So i changed the path like this then it worked.
import foo from '../../../src/components/foo';
Tes passed everything is looks fine. But we still have the path problem in test files.
Lets try to import another component in foo component.
foo.js
import bar from 'components/admin/bar';
Here is the second problem. Test file FAILED error message is
Cannot find module 'components/admin/bar' from 'foo.js'
I moved my test file in to my foo.js file. But didn't worked.
Here is my whole webpack.config.js
import webpack from 'webpack';
import HtmlWebpackPlugin from 'html-webpack-plugin';
import autoprefixer from 'autoprefixer';
import path from 'path';
export default {
resolve: {
modules: [
'node_modules',
path.resolve(__dirname, 'src')
],
extensions: ['*', '.js', '.jsx', '.json']
},
devtool: 'inline-source-map', // more info:https://webpack.github.io/docs/build-performance.html#sourcemaps and https://webpack.github.io/docs/configuration.html#devtool
entry: [
// must be first entry to properly set public path
'./src/webpack-public-path',
'webpack-hot-middleware/client?reload=true',
path.resolve(__dirname, 'src/index.js') // Defining path seems necessary for this to work consistently on Windows machines.
],
target: 'web', // necessary per https://webpack.github.io/docs/testing.html#compile-and-test
output: {
path: path.resolve(__dirname, 'dist'), // Note: Physical files are only output by the production build task `npm run build`.
publicPath: '/',
filename: 'bundle.js'
},
plugins: [
new webpack.DefinePlugin({
'process.env.NODE_ENV': JSON.stringify('development'), // Tells React to build in either dev or prod modes. https://facebook.github.io/react/downloads.html (See bottom)
__DEV__: true,
//'API_URL': API_URL.dev
}),
new webpack.HotModuleReplacementPlugin(),
new webpack.NoEmitOnErrorsPlugin(),
new HtmlWebpackPlugin({ // Create HTML file that includes references to bundled CSS and JS.
template: 'src/index.ejs',
minify: {
removeComments: true,
collapseWhitespace: true
},
inject: true
}),
new webpack.LoaderOptionsPlugin({
minimize: false,
debug: true,
noInfo: true, // set to false to see a list of every file being bundled.
options: {
sassLoader: {
includePaths: [path.resolve(__dirname, 'src', 'scss')]
},
context: '/',
postcss: () => [autoprefixer],
}
})
],
module: {
rules: [
{test: /\.jsx?$/, exclude: /node_modules/, loaders: ['babel-loader']},
{test: /\.eot(\?v=\d+.\d+.\d+)?$/, loader: 'file-loader'},
{
test: /\.woff(2)?(\?v=[0-9]\.[0-9]\.[0-9])?$/,
loader: 'url-loader?limit=10000&mimetype=application/font-woff'
},
{test: /\.[ot]tf(\?v=\d+.\d+.\d+)?$/, loader: 'url-loader?limit=10000&mimetype=application/octet-stream'},
{test: /\.svg(\?v=\d+\.\d+\.\d+)?$/, loader: 'url-loader?limit=10000&mimetype=image/svg+xml'},
{test: /\.(jpe?g|png|gif)$/i, loader: 'file-loader?name=[name].[ext]'},
{test: /\.ico$/, loader: 'file-loader?name=[name].[ext]'},
{
test: /(\.css|\.scss|\.sass)$/,
loaders: ['style-loader', 'css-loader?sourceMap', 'postcss-loader', 'sass-loader?sourceMap']
}
]
}
};
How can i solve?
Thanks for your help.

Webpack is not used during test execution. Since you are using babel the babel-plugin-module-resolver https://github.com/tleunen/babel-plugin-module-resolver should solve the issue:
in your .babelrc file
{
"plugins": [
["module-resolver", {
"root": ["./src"]
}]
]
}
A more cleaner approach would be to create an alias in your .babelrc file and then import from that alias, for instance:
{
"plugins": [
["module-resolver", {
"alias": {
"#app": "./src"
}
}]
]
}
And in your file:
import foo from '#app/components/foo'
That way you have no naming conflicts and your paths are nice and short.

Problem solved after i changed this jest object in package.json file.
"jest": {
"moduleDirectories": [
"node_modules",
"src"
]
...