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How to transpile and minify single file with webpack?

I have a React application, and in my application I'm relying on react-scripts, so the build command is defined like this "build": "react-scripts build", and it works all fine. Now, the point is that inside my src directory I have a JS file called wrapper.js, which is a standalone file, and it is pure JS, no React stuff, but it uses ES6 and some newer features. So, what I want to do is that, I want create a new command, which will transpile and minify this file and will create a standalone copy of it. I thought to use webpack and I created a webpack.config.js file in the root of my project, which looks like this:
const path = require('path');
const MinifyPlugin = require('babel-minify-webpack-plugin');
module.exports = {
mode: 'production',
output: {
path: __dirname + 'build',
publicPath: '/build/',
filename: 'wrapper.js',
},
module: {
rules: [
{
test: /\.js$/,
include: [
path.resolve(__dirname, 'src', 'wrapper.js')
],
use: {
loader: 'babel-loader',
options: {
presets: ['env']
}
}
}
]
},
plugins: [
new MinifyPlugin()
]
};
And I added the following to my package.json file "wrapper": "webpack". Now, when I run npm run-scripts wrapper, it executes the webpack command, but it throws error. The output looks like this:
> webpack
Hash: 0aa67383ec371b8b7cd1
Version: webpack 4.19.1
Time: 362ms
Built at: 04/06/2019 10:54:46 AM
1 asset
Entrypoint main = wrapper.js
[0] ./src/index.js 223 bytes {0} [built] [failed] [1 error]
ERROR in ./src/index.js 22:4
Module parse failed: Unexpected token (22:4)
You may need an appropriate loader to handle this file type.
|
| ReactDOM.render(
> <Root />,
| document.getElementById('root'),
| );
What I see is that the problem is that webpack also tries to transpile and minify other files in my src directory, because it seems it has hit my React app's index.js file. How can I exclude everything? Or more precisely, how can I tell webpack to transpile and minify only the file /src/wrapper.js, and not to touch anything else at all?

Lighter weight alternative could be to create a script in your package.json and use babel-minify, https://babeljs.io/docs/en/babel-minify
package.json
{
...
"scripts": : {
"minify": "minify wrapper.js --out-file wrapper.min.js --mangle.keepClassName"
}
...
}

Add entry object to your webpack.config.js.
module.exports={
entry: './src/wrapper.js',
...
}
webpack points the entry object by default to ./src/index.js.
So if you don't override entry object, webpack will bundle the file in ./src/index.js
Update
To point to a output directory properly
output: {
filename: 'wrapper.js',
path: path.resolve(__dirname, 'build')
}

How to import CSS files into webpack?

According to the documentation, CSS file should just be imported.
I am just starting with webpack and tried to import a CSS file but I get a message about a module missing:
D:\Dropbox\dev\jekyll\blog>webpack --display-error-details
Hash: 0cabc1049cbcbdb8d134
Version: webpack 2.6.1
Time: 74ms
Asset Size Chunks Chunk Names
build.js 2.84 kB 0 [emitted] main
[0] ./webpack/entry.js 47 bytes {0} [built]
ERROR in ./webpack/entry.js
Module not found: Error: Can't resolve 'navbar.css' in 'D:\Dropbox\dev\jekyll\blog\webpack'
resolve 'navbar.css' in 'D:\Dropbox\dev\jekyll\blog\webpack'
Parsed request is a module
using description file: D:\Dropbox\dev\jekyll\blog\package.json (relative path: ./webpack)
Field 'browser' doesn't contain a valid alias configuration
after using description file: D:\Dropbox\dev\jekyll\blog\package.json (relative path: ./webpack)
resolve as module
D:\Dropbox\dev\jekyll\blog\webpack\node_modules doesn't exist or is not a directory
D:\Dropbox\dev\jekyll\node_modules doesn't exist or is not a directory
D:\Dropbox\dev\node_modules doesn't exist or is not a directory
D:\Dropbox\node_modules doesn't exist or is not a directory
D:\node_modules doesn't exist or is not a directory
looking for modules in D:\Dropbox\dev\jekyll\blog\node_modules
using description file: D:\Dropbox\dev\jekyll\blog\package.json (relative path: ./node_modules)
Field 'browser' doesn't contain a valid alias configuration
after using description file: D:\Dropbox\dev\jekyll\blog\package.json (relative path: ./node_modules)
using description file: D:\Dropbox\dev\jekyll\blog\package.json (relative path: ./node_modules/navbar.css)
as directory
D:\Dropbox\dev\jekyll\blog\node_modules\navbar.css doesn't exist
no extension
Field 'browser' doesn't contain a valid alias configuration
D:\Dropbox\dev\jekyll\blog\node_modules\navbar.css doesn't exist
.js
Field 'browser' doesn't contain a valid alias configuration
D:\Dropbox\dev\jekyll\blog\node_modules\navbar.css.js doesn't exist
.json
Field 'browser' doesn't contain a valid alias configuration
D:\Dropbox\dev\jekyll\blog\node_modules\navbar.css.json doesn't exist
[D:\Dropbox\dev\jekyll\blog\webpack\node_modules]
[D:\Dropbox\dev\jekyll\node_modules]
[D:\Dropbox\dev\node_modules]
[D:\Dropbox\node_modules]
[D:\node_modules]
[D:\Dropbox\dev\jekyll\blog\node_modules\navbar.css]
[D:\Dropbox\dev\jekyll\blog\node_modules\navbar.css]
[D:\Dropbox\dev\jekyll\blog\node_modules\navbar.css.js]
[D:\Dropbox\dev\jekyll\blog\node_modules\navbar.css.json]
# ./webpack/entry.js 1:0-21
webpack is ran against the following webpack.config.js:
const path = require('path');
module.exports = {
entry: path.join(__dirname, 'webpack/entry.js'),
output: {
path: path.join(__dirname, 'dist'),
filename: 'build.js'
},
module: {
loaders: [
{
test: /\.js$/,
loader: 'babel-loader',
exclude: /node_modules/
}
],
rules: [{
test: /\.css$/,
use: [ 'style-loader', 'css-loader' ]
}]
}
}
I initially thought (before using --display-error-details) that this was due to some problems with the path structure (specifically forward vs. backward slashes) but then moved navbar.css into the root of the folder webpack - same issue.
The detailed error shows that the CSS file is sought after in nodes_module (which is hunted down though all the directories tree). Why? How should I then import a file which is in webpack/static/css/myfile.css relative to the location of webpack.config.js?
Note: the same issue exists when trying require instead of import

You have to import them like any JavaScript module. That means, when the imported file is neither a relative path (starting with ../ or ./), nor an absolute path (starting with /), it is resolved as a module. By default webpack will look for modules in the node_modules directory (in the current directory and all parent directories). This is the same behaviour that Node.js uses.
To import webpack/static/css/myfile.css in webpack/entry.js you have to use a relative path.
import './static/css/myfile.css';
If you don't want to use a relative path, you can change the directories that webpack uses to find a module with the resolve.modules or you can use resolve.alias.
In your webpack config you also defined both module.rules and module.loaders. When webpack sees module.rules it ignores module.loaders completely, so your babel-loader wouldn't be used. You should only use module.rules.
module: {
rules: [
{
test: /\.js$/,
loader: 'babel-loader',
exclude: /node_modules/
},
{
test: /\.css$/,
use: ['style-loader', 'css-loader']
}
]
}

For some reason; nothing worked for me so I added the css file to my list in entry:
// webpack.config.js
module.exports = {
// ...
entry: ["./src/style.css", "./src/index.js"]
// ...
}

#Aakash try adding sideEffects: true to css-loader rule like this:
test: /\.css$/
sideEffects: true,
use: [...]
Looks like webpack treats project css files like a dead code.
Found this workaround at cra config.

Making a library importable using webpack and babel

I am trying to publish a package on npm (this one) that I am developing using webpack and babel. My code is written in ES6. I have a file in my sources, index.js, that (for the moment) exports one of my library's core components, it simply goes like this:
import TheGamesDb from './scrapers/thegamesdb';
export { TheGamesDb };
I am using webpack and babel to create a dist index.js that is my package's main file. My webpack.config.js goes like this:
const webpack = require('webpack');
const nodeExternals = require('webpack-node-externals');
module.exports = {
entry: {
index: ['babel-polyfill', './src/index.js'],
development: ['babel-polyfill', './src/development.js']
},
output: {
path: '.',
filename: '[name].js',
library: 'rom-scraper',
libraryTarget: 'umd',
umdNamedDefine: true
},
devtool: 'source-map',
module: {
loaders: [
{ test: /\.js$/, loader: 'babel-loader', exclude: /node_modules/ }
]
},
target: 'node',
externals: [nodeExternals()]
};
Now when I load my package in another project and try to import my export TheGamesDb simply like this
import { TheGamesDb } from 'rom-scraper';
I get the error
Uncaught TypeError: Path must be a string. Received undefined
It is to be noted that I am importing my library in electron.
Update: Electron seems to be the main problem here and it is not even my library but a dependency that throws this error (only in Electron)

The problem wasn't any of the things in my question but node-expat not working in electron. I switched to an alternative library and it's all right now.

Webpack throws syntax error for JSX

When I attempted to use webpack to compile my react jsx code, I received the following error:
ERROR in ./client/index.js
Module parse failed: C:\Users\Gum-Joe\Documents\Projects\bedel/client\index.js Unexpected token (6:11)
You may need an appropriate loader to handle this file type.
SyntaxError: Unexpected token (6:11)
at Parser.pp.raise (C:\Users\Gum-Joe\Documents\Projects\bedel\node_modules\acorn\dist\acorn.js:920:13)
at Parser.pp.unexpected (C:\Users\Gum-Joe\Documents\Projects\bedel\node_modules\acorn\dist\acorn.js:1483:8)
at Parser.pp.parseExprAtom (C:\Users\Gum-Joe\Documents\Projects\bedel\node_modules\acorn\dist\acorn.js:330:12)
at Parser.pp.parseExprSubscripts (C:\Users\Gum-Joe\Documents\Projects\bedel\node_modules\acorn\dist\acorn.js:225:19)
at Parser.pp.parseMaybeUnary (C:\Users\Gum-Joe\Documents\Projects\bedel\node_modules\acorn\dist\acorn.js:204:17)
at Parser.pp.parseExprOps (C:\Users\Gum-Joe\Documents\Projects\bedel\node_modules\acorn\dist\acorn.js:151:19)
at Parser.pp.parseMaybeConditional (C:\Users\Gum-Joe\Documents\Projects\bedel\node_modules\acorn\dist\acorn.js:133:19)
at Parser.pp.parseMaybeAssign (C:\Users\Gum-Joe\Documents\Projects\bedel\node_modules\acorn\dist\acorn.js:110:19)
at Parser.pp.parseExpression (C:\Users\Gum-Joe\Documents\Projects\bedel\node_modules\acorn\dist\acorn.js:86:19)
at Parser.pp.parseReturnStatement (C:\Users\Gum-Joe\Documents\Projects\bedel\node_modules\acorn\dist\acorn.js:1854:26)
at Parser.pp.parseStatement (C:\Users\Gum-Joe\Documents\Projects\bedel\node_modules\acorn\dist\acorn.js:1719:19)
at Parser.pp.parseBlock (C:\Users\Gum-Joe\Documents\Projects\bedel\node_modules\acorn\dist\acorn.js:1991:21)
at Parser.pp.parseFunctionBody (C:\Users\Gum-Joe\Documents\Projects\bedel\node_modules\acorn\dist\acorn.js:607:22)
at Parser.pp.parseMethod (C:\Users\Gum-Joe\Documents\Projects\bedel\node_modules\acorn\dist\acorn.js:576:8)
at Parser.pp.parseClassMethod (C:\Users\Gum-Joe\Documents\Projects\bedel\node_modules\acorn\dist\acorn.js:2137:23)
at Parser.pp.parseClass (C:\Users\Gum-Joe\Documents\Projects\bedel\node_modules\acorn\dist\acorn.js:2122:10)
# ./client/index.js 1:0-20
.babelrc:
{
"presets": ["es2015", "react"]
}
webpack.config.js:
// Webpack config
const path = require('path');
const webpack = require('webpack');
const HtmlWebpackPlugin = require('html-webpack-plugin');
module.exports = {
// Use client as our root
context: __dirname + "/client",
// Entry file
entry: "./index.js",
// Resolve
resolve: {
extensions: ['', '.js', '.jsx']
},
// Output to /build
output: {
path: path.join(__dirname, "build", "js"),
filename: "bundle.js"
},
loaders: [
{ test: /\.jsx$/, exclude: /node_modules/, loader: "babel-loader" }
],
// Plugins
plugins: [
// HTML
new HtmlWebpackPlugin({
title: 'Bedel',
filename: path.join(__dirname, 'views', 'index.ejs'),
template: path.join(__dirname, 'client', 'templates', 'index.ejs')
})
]
};
index.js:
import React from 'react';
import ReactDOM from 'react-dom';
class App extends React.Component {
render () {
return <p> Hello React</p>;
}
}
ReactDOM.render(<App/>, document.getElementById('app'));
I have installed all the babel presets required, as well as babel-core.
I have looked at the following answers already:
babel-loader jsx SyntaxError: Unexpected token
React, babel, webpack not parsing jsx code
Edit: After commenting out my jsx syntax, the outputting bundle.js does not appear to have been transformed by babel (i.e. I can see ES6 code in it)
Edit: Sorry for the inconvenience, but app.jsx was a solution that I tried that involved putting the logic that should be in index.js into a separate file.
Edit: Here is a list of the solutions I tried that did not work:
Copy .babelrc to client/.babelrc
Change test to test for .js instead of .js
Separate app logic into separate file (app.js)
Put presets to use in webpack config
Also, I have pushed my code to my GitHub repo (https://github.com/Gum-Joe/bedel). Feel free to have a look at it.

You configured the loader to only pass .jsx files through Babel:
test: /\.jsx$/
However, your file has the extension .js. Either rename the file or update the test expression to /\.jsx?$/.
In addition to updating the test, you need to rename .babel.rc to .babelrc (no . before rc). Otherwise Babel thinks that there is no configuration file and won't load any presets.

The loaders property must exist within the module property. Webpack Loaders
module.exports = {
// ...
// Output to /build
output: {
path: path.join(__dirname, "build", "js"),
filename: "bundle.js"
},
module: {
loaders: [
{ test: /\.jsx$/, exclude: /node_modules/, loader: "babel-loader" }
]
},
//...
};

You need to use react-preset with babel, like here:
loaders: [{
test: /\.(js|jsx)$/,
loader: 'babel',
query: {
presets: [
'es2015',
'react'
]
}
}]

I'm having this issue as well, and if you're using Windows and Node 6.x, the only workaround I've found for now seems to be to use Node 4 LTS or 5 instead. Without knowing the root cause, the problem seems to stem from some combination of using JSX, Webpack, Babel, Acorn JS, Node 6, and Windows.
https://github.com/coryhouse/pluralsight-redux-starter/issues/2
https://github.com/danmartinez101/babel-preset-react-hmre/issues/32

Can you try wrapping the entire element in brackets "()"?
return (<p>...</p>)

Webpack: node_modules/css/index.js didn't return a function

I'm trying out webpack for the first time and used this tutorial to get started and include react.js.
After finishing the steps and installing the style and css module I keep getting an error that the css module didn't return a function.
This is my index.jsx:
/** #jsx React.DOM */
'use strict';
require('../css/normalize.css');
var React = require('react');
var Hello = require('./Test/Hello');
React.render(<Hello />, document.getElementById('content'));
And my webpack config file:
module.exports = {
entry: './ui/src/index.jsx',
output: {
path: __dirname + '/build-ui',
filename: 'app.js', //this is the default name, so you can skip it
//at this directory our bundle file will be available
//make sure port 8090 is used when launching webpack-dev-server
publicPath: 'http://localhost:8090/assets'
},
module: {
loaders: [
{
//tell webpack to use jsx-loader for all *.jsx files
test: /\.jsx$/,
loader: 'jsx-loader?insertPragma=React.DOM&harmony'
},
{
test: /\.css$/,
loader: "style!css"
},
{
test: /\.scss$/,
loader: "style!css!sass"
}
]
},
externals: {
//don't bundle the 'react' npm package with our bundle.js
//but get it from a global 'React' variable
'react': 'React'
},
resolve: {
extensions: ['', '.js', '.jsx']
}
};
When webpack tries to bundle the project it always states the following error:
ERROR in Loader /Users/Johannes/Documents/Development/holmes/node_modules/css/index.js didn't return a function
# ./ui/src/index.jsx 5:0-31
I don't know what to do about that. Has anyone encountered that issue? And how can I solve it?
EDIT: My directory looks as follows:
holmes/
ui/
css/
normalize.css
src/
Test/
Hello.jsx
index.jsx
index.html
package.json
webpack.config.js

This error is caused by a css module inside node_modules. Since you've specified the css-loader in your config, webpack tries to lookup that loader inside node_modules and finds another module called css which doesn't look like a loader (hence the error message).
To avoid confusion you should simply add the -loader postfix to each loader. Omitting the -loader postfix is just a convenience feature by webpack, but unfortunately it's the culprit of that error in your case.
loaders: [
{
//tell webpack to use jsx-loader for all *.jsx files
test: /\.jsx$/,
loader: 'jsx-loader?insertPragma=React.DOM&harmony'
},
{
test: /\.css$/,
loader: "style-loader!css-loader"
},
{
test: /\.scss$/,
loader: "style-loader!css-loader!sass-loader"
}
Update: Starting with webpack 2, you can't omit the -loader postfix anymore. We decided to do this to prevent errors like this.

I had a similar issue with react-flexbox-grid. In my case, the solution was installing css-loader and style-loader npm modules:
npm install css-loader style-loader --save-dev

I also came across a similar issue using node-noop.
Fortunately, using null as a replacement worked when I added enzyme and react-addons-test-utils to a project.