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webpack and importing js files to scripts and bundling up

I'm pretty inexperienced with webpack. I'm actually using Cloudflare Wrangler, which I believe uses Webpack 4 under the hood. In any case I have an src/index.js file and a helpers/script.js file.
my index.js file works fine, builds and compiles etc etc.
When I copy the content of helpers/script.js into the top of the index.js file, again all is good and works.
When I import script.js with either of
import human from "../helpers/script"
const human = require("../helpers/script")
then I use a webpack.config.js file that looks like
module.exports = {
target: 'webworker',
context: __dirname,
entry: './src/index.js',
mode: 'production',
module: {
rules: [
{
test: /\.index\.js$/,
use: { loader: 'worker-loader' }
}
],
},
resolve: {
extensions: ['.js'],
},
};
I can't seem, no matter what I do to get it to 'like' the imported script file.
I continually get:
You may need an appropriate loader to handle this file type, currently no loaders are configured to process this file. See https://webpack.js.org/concepts#loaders
...
Error: webpack returned an error. Try configuring `entry` in your webpack config relative to the current working directory, or setting `context = __dirname` in your webpack config.
Can anyone help me understand the requirements for being able to import a file to another js. Its amazing how hard this is to do :joy:

How to Make Webpack Produce a JS file as-is to Use it Later for Configuration [duplicate]

I'm trying to move from Gulp to Webpack. In Gulp I have task which copies all files and folders from /static/ folder to /build/ folder. How to do the same with Webpack? Do I need some plugin?

Requiring assets using the file-loader module is the way webpack is intended to be used (source). However, if you need greater flexibility or want a cleaner interface, you can also copy static files directly using my copy-webpack-plugin (npm, Github). For your static to build example:
const CopyWebpackPlugin = require('copy-webpack-plugin');
module.exports = {
context: path.join(__dirname, 'your-app'),
plugins: [
new CopyWebpackPlugin({
patterns: [
{ from: 'static' }
]
})
]
};
Compatibility note: If you're using an old version of webpack like webpack#4.x.x, use copy-webpack-plugin#6.x.x. Otherwise use latest.

You don't need to copy things around, webpack works different than gulp. Webpack is a module bundler and everything you reference in your files will be included. You just need to specify a loader for that.
So if you write:
var myImage = require("./static/myImage.jpg");
Webpack will first try to parse the referenced file as JavaScript (because that's the default). Of course, that will fail. That's why you need to specify a loader for that file type. The file- or url-loader for instance take the referenced file, put it into webpack's output folder (which should be build in your case) and return the hashed url for that file.
var myImage = require("./static/myImage.jpg");
console.log(myImage); // '/build/12as7f9asfasgasg.jpg'
Usually loaders are applied via the webpack config:
// webpack.config.js
module.exports = {
...
module: {
loaders: [
{ test: /\.(jpe?g|gif|png|svg|woff|ttf|wav|mp3)$/, loader: "file" }
]
}
};
Of course you need to install the file-loader first to make this work.

If you want to copy your static files you can use the file-loader in this way :
for html files :
in webpack.config.js :
module.exports = {
...
module: {
loaders: [
{ test: /\.(html)$/,
loader: "file?name=[path][name].[ext]&context=./app/static"
}
]
}
};
in your js file :
require.context("./static/", true, /^\.\/.*\.html/);
./static/ is relative to where your js file is.
You can do the same with images or whatever.
The context is a powerful method to explore !!

One advantage that the aforementioned copy-webpack-plugin brings that hasn't been explained before is that all the other methods mentioned here still bundle the resources into your bundle files (and require you to "require" or "import" them somewhere). If I just want to move some images around or some template partials, I don't want to clutter up my javascript bundle file with useless references to them, I just want the files emitted in the right place. I haven't found any other way to do this in webpack. Admittedly it's not what webpack originally was designed for, but it's definitely a current use case.
(#BreakDS I hope this answers your question - it's only a benefit if you want it)

Webpack 5 adds Asset Modules which are essentially replacements for common file loaders. I've copied a relevant portion of the documentation below:
asset/resource emits a separate file and exports the URL. Previously achievable by using file-loader.
asset/inline exports a data URI of the asset. Previously achievable by using url-loader.
asset/source exports the source code of the asset. Previously achievable by using raw-loader.
asset automatically chooses between exporting a data URI and emitting a separate file. Previously achievable by using url-loader with asset size limit.
To add one in you can make your config look like so:
// webpack.config.js
module.exports = {
...
module: {
rules: [
{
test: /\.(jpe?g|gif|png|svg|woff|ttf|wav|mp3)$/,
type: "asset/resource"
}
]
}
};
To control how the files get output, you can use templated paths.
In the config you can set the global template here:
// webpack.config.js
module.exports = {
...
output: {
...
assetModuleFilename: '[path][name].[hash][ext][query]'
}
}
To override for a specific set of assets, you can do this:
// webpack.config.js
module.exports = {
...
module: {
rules: [
{
test: /\.(jpe?g|gif|png|svg|woff|ttf|wav|mp3)$/,
type: "asset/resource"
generator: {
filename: '[path][name].[hash][ext][query]'
}
}
]
}
};
The provided templating will result in filenames that look like build/images/img.151cfcfa1bd74779aadb.png. The hash can be useful for cache busting etc. You should modify to your needs.

Above suggestions are good. But to try to answer your question directly I'd suggest using cpy-cli in a script defined in your package.json.
This example expects node to somewhere on your path. Install cpy-cli as a development dependency:
npm install --save-dev cpy-cli
Then create a couple of nodejs files. One to do the copy and the other to display a checkmark and message.
copy.js
#!/usr/bin/env node
var shelljs = require('shelljs');
var addCheckMark = require('./helpers/checkmark');
var path = require('path');
var cpy = path.join(__dirname, '../node_modules/cpy-cli/cli.js');
shelljs.exec(cpy + ' /static/* /build/', addCheckMark.bind(null, callback));
function callback() {
process.stdout.write(' Copied /static/* to the /build/ directory\n\n');
}
checkmark.js
var chalk = require('chalk');
/**
* Adds mark check symbol
*/
function addCheckMark(callback) {
process.stdout.write(chalk.green(' ✓'));
callback();
}
module.exports = addCheckMark;
Add the script in package.json. Assuming scripts are in <project-root>/scripts/
...
"scripts": {
"copy": "node scripts/copy.js",
...
To run the sript:
npm run copy

The way I load static images and fonts:
module: {
rules: [
....
{
test: /\.(jpe?g|png|gif|svg)$/i,
/* Exclude fonts while working with images, e.g. .svg can be both image or font. */
exclude: path.resolve(__dirname, '../src/assets/fonts'),
use: [{
loader: 'file-loader',
options: {
name: '[name].[ext]',
outputPath: 'images/'
}
}]
},
{
test: /\.(woff(2)?|ttf|eot|svg|otf)(\?v=\d+\.\d+\.\d+)?$/,
/* Exclude images while working with fonts, e.g. .svg can be both image or font. */
exclude: path.resolve(__dirname, '../src/assets/images'),
use: [{
loader: 'file-loader',
options: {
name: '[name].[ext]',
outputPath: 'fonts/'
},
}
]
}
Don't forget to install file-loader to have that working.

You can write bash in your package.json:
# package.json
{
"name": ...,
"version": ...,
"scripts": {
"build": "NODE_ENV=production npm run webpack && cp -v <this> <that> && echo ok",
...
}
}

Most likely you should use CopyWebpackPlugin which was mentioned in kevlened answer. Alternativly for some kind of files like .html or .json you can also use raw-loader or json-loader. Install it via npm install -D raw-loader and then what you only need to do is to add another loader to our webpack.config.js file.
Like:
{
test: /\.html/,
loader: 'raw'
}
Note: Restart the webpack-dev-server for any config changes to take effect.
And now you can require html files using relative paths, this makes it much easier to move folders around.
template: require('./nav.html')

I was stuck here too. copy-webpack-plugin worked for me.
However, 'copy-webpack-plugin' was not necessary in my case (i learned later).
webpack ignores root paths
example
<img src="/images/logo.png'>
Hence, to make this work without using 'copy-webpack-plugin'
use '~' in paths
<img src="~images/logo.png'>
'~' tells webpack to consider 'images' as a module
note:
you might have to add the parent directory of images directory in
resolve: {
modules: [
'parent-directory of images',
'node_modules'
]
}
Visit https://vuejs-templates.github.io/webpack/static.html

The webpack config file (in webpack 2) allows you to export a promise chain, so long as the last step returns a webpack config object. See promise configuration docs. From there:
webpack now supports returning a Promise from the configuration file. This allows to do async processing in you configuration file.
You could create a simple recursive copy function that copies your file, and only after that triggers webpack. E.g.:
module.exports = function(){
return copyTheFiles( inpath, outpath).then( result => {
return { entry: "..." } // Etc etc
} )
}

lets say all your static assets are in a folder "static" at the root level and you want copy them to the build folder maintaining the structure of subfolder, then
in your entry file) just put
//index.js or index.jsx
require.context("!!file?name=[path][name].[ext]&context=./static!../static/", true, /^\.\/.*\.*/);

In my case I used webpack for a wordpress plugin to compress js files, where the plugin files are already compressed and need to skip from the process.
optimization: {
minimize: false,
},
externals: {
"jquery": "jQuery",
},
entry: glob.sync('./js/plugin/**.js').reduce(function (obj, el) {
obj[path.parse(el).name] = el;
return obj
}, {}),
output: {
path: path.resolve(__dirname, './js/dist/plugin'),
filename: "[name].js",
clean: true,
},
That used to copy the js file as it is to the build folder. Using any other methods like file-loader and copy-webpack create issues with that.
Hope it will help someone.

Gulp to Webpack migration on an old website - generating vendors from non-npm dependencies

We want to migrate from gulp to webpack on a rather big and old website. Gulp just concat and minify JS & CSS files at the moment. I want to migrate to webpack because another front dev made some react modules that are compiled by browserify cmd in another folder:
we work in a webapp/ folder, minified files are located here :
js/app.min.js
jslib/vendors.min.js
css/app.min.css
sources files are :
js/
file1.js
file2.js
...
jslib/
jquery-1.11.2.min.js
jquery.fancybox.js
...
jquery.very-old-dependency-not-on-npm.min.js
css/
style.css
extra.css
my goal is to keep this file split for javascript by using two files, app.js and vendors.js. These 2 files should be, ideally, ES6 files that import other files.
Actually i'm looking for a way to do a simple concatenation / minification of JS files through the 2 es6 files with imports. Webpack is checking for dependencies and to overcome the "jquery is not defined" errors i added the webpack.providePlugin and the resolve.alias part in webpack.config. But this loads jquery in my app.min.js file and i don't want it for performance purposes. I'm aware that all libs should be npm installed and required/imported in es6 context for an optimized webpack use, but some old jquery libs are not available on npm in the version i want so i have to go with the files already in the project.
vendors.js :
import "./jquery-1.11.2.min.js";
import "./jquery.fancybox.js"
app.js :
import "./file1.js"
import "./file2.js"
webpack.config.js
const path = require('path')
const webpack = require('webpack')
module.exports = {
entry: {
'/../../js/app': path.resolve(__dirname + '/../../js/app.js'),
'/../../jslib/vendors': path.resolve(__dirname + '/../../jslib/vendors.js'),
},
output: {
path: path.resolve(__dirname),
filename: '[name].min.js',
},
module: {
rules: [
{
test: /\.(js|jsx)$/,
exclude: /node_modules/,
use: {
loader: 'babel-loader',
},
},
],
},
plugins: [
new webpack.ProvidePlugin({
$: 'jquery',
jQuery: 'jquery',
'window.jQuery': 'jquery'
}),
],
resolve: {
alias: {
jquery: path.resolve(__dirname+'/../../jslib/jquery-1.11.2.min.js')
},
},
}
all my paths are ok (the folder location of the current gulp / future webpack is not in assets folder ) and webpack is successfully running, i just want to find a clean way to perform a simple concat / minify without including jquery in my app file before going further.

Here is an example of using jquery in an html file external
As for the names of app and vendors, you must change this part
entry: {
'/../../js/app': path.resolve(__dirname + '/../../js/app.js'),
'/../../jslib/vendors': path.resolve(__dirname + '/../../jslib/vendors.js'),
},
for this
entry: {
app: path.resolve(__dirname + '/../../js/app.js'),
vendors: path.resolve(__dirname + '/../../jslib/vendors.js'),
},
Do not add jquery to import if you want it to be added from outside. Remove jquery from vendors.js
I hope I helped.

webpack babel how to copy transpiled file if i don't use import/require

I have a file in my project called test.js
I don't import/require it anywhere which means my webpack won't call babel-loader for that js file.
Question: what I want is to move test.js into /dist folder, but as a compiled/transpiled. What's the best practice for it?
What I tried: I tried to use a copy-webpack-plugin and use its transform parameters before copying the file, but I can't seem to find the good babel package.
{
from: 'test.js',
to: '/dist/test.js',
transform(content, path) {
//what do I write here?
},
}

The simplest approach I could think about is to use several entry points like this:
{
entry: {
a: "./your-main-stuff",
b: "./your-single-file",
},
output: {
path: path.join(__dirname, "dist"),
filename: "[name].js"
}
}
which will create your a.js main bundle and b.js file in __dirname/dist folder both transpiled provided you used corresponding loader(s).
And from copy-webpack-plugin docs section:
webpack-copy-plugin is not designed to copy files generated from the
build process; rather, it is to copy files that already exist in the
source tree, as part of the build process.
so it seems to be difficult (if possible) making it move transpiled files.
Update. If you want to output files into different folders w/o changing your src folder, additonal tools needed. For your case (just 1 file) I would write a simple script and add it into package.json script section combined with webpack call like:
"scripts": {
"dev": "webpack && babel path-to-script.js --out-file path-to-script-compiled.js"
}

Just like in the previous answer, initially I went with the "scripts" entry in package.json that runs babel. But for a number of reasons I wanted to use webpack 5 to do the job. So after failing with webpack-copy-plugin and a good amount of digging around I came to this solution:
let config = {
entry: [
glob.sync(srcDir + '/**/*.js') // get all .js files from the source dir
],
output : {
filename : '[name].rem.js', // webpack wants to bundle - it can bundle here ;)
path: outDir
},
resolve: {
alias: {
'app': appDir
}
},
plugins: [
new RemoveEmptyScriptsPlugin({extensions: ['js'], scriptExtensions: /\.rem\.js/}) // for all .js source files that get bundled remove the bundle .rem.js file
],
module: {
rules:[{
test: /\.jsx?$/,
type: 'asset/resource', // get webpack to take it out instead of bundling
generator: {
filename: ({filename}) => filename // return full file name so directory structure is preserved
},
use: {
loader: 'babel-loader',
options: {
targets: { node: 16 },
presets: [
['#babel/preset-env', { modules: 'commonjs' /* transpile import/export */}],
]
}
}
}]
}
};
// Since the code does not go through the full pipeline and imports are not getting resolved, aliases will remain in the code.
// To resolve them it takes to hack the aliases object into the babel config
config.module.rules[0].use.options.plugins.push(['babel-plugin-webpack-alias-7', {config: {resolve: {alias: config.resolve.alias}}}];
And it does a good job but beware that it takes to use the patched versions of the two plugins (unless the patches have been merged already)!

How to copy static files to build directory with Webpack?

I'm trying to move from Gulp to Webpack. In Gulp I have task which copies all files and folders from /static/ folder to /build/ folder. How to do the same with Webpack? Do I need some plugin?

Requiring assets using the file-loader module is the way webpack is intended to be used (source). However, if you need greater flexibility or want a cleaner interface, you can also copy static files directly using my copy-webpack-plugin (npm, Github). For your static to build example:
const CopyWebpackPlugin = require('copy-webpack-plugin');
module.exports = {
context: path.join(__dirname, 'your-app'),
plugins: [
new CopyWebpackPlugin({
patterns: [
{ from: 'static' }
]
})
]
};
Compatibility note: If you're using an old version of webpack like webpack#4.x.x, use copy-webpack-plugin#6.x.x. Otherwise use latest.

You don't need to copy things around, webpack works different than gulp. Webpack is a module bundler and everything you reference in your files will be included. You just need to specify a loader for that.
So if you write:
var myImage = require("./static/myImage.jpg");
Webpack will first try to parse the referenced file as JavaScript (because that's the default). Of course, that will fail. That's why you need to specify a loader for that file type. The file- or url-loader for instance take the referenced file, put it into webpack's output folder (which should be build in your case) and return the hashed url for that file.
var myImage = require("./static/myImage.jpg");
console.log(myImage); // '/build/12as7f9asfasgasg.jpg'
Usually loaders are applied via the webpack config:
// webpack.config.js
module.exports = {
...
module: {
loaders: [
{ test: /\.(jpe?g|gif|png|svg|woff|ttf|wav|mp3)$/, loader: "file" }
]
}
};
Of course you need to install the file-loader first to make this work.

If you want to copy your static files you can use the file-loader in this way :
for html files :
in webpack.config.js :
module.exports = {
...
module: {
loaders: [
{ test: /\.(html)$/,
loader: "file?name=[path][name].[ext]&context=./app/static"
}
]
}
};
in your js file :
require.context("./static/", true, /^\.\/.*\.html/);
./static/ is relative to where your js file is.
You can do the same with images or whatever.
The context is a powerful method to explore !!

One advantage that the aforementioned copy-webpack-plugin brings that hasn't been explained before is that all the other methods mentioned here still bundle the resources into your bundle files (and require you to "require" or "import" them somewhere). If I just want to move some images around or some template partials, I don't want to clutter up my javascript bundle file with useless references to them, I just want the files emitted in the right place. I haven't found any other way to do this in webpack. Admittedly it's not what webpack originally was designed for, but it's definitely a current use case.
(#BreakDS I hope this answers your question - it's only a benefit if you want it)

Webpack 5 adds Asset Modules which are essentially replacements for common file loaders. I've copied a relevant portion of the documentation below:
asset/resource emits a separate file and exports the URL. Previously achievable by using file-loader.
asset/inline exports a data URI of the asset. Previously achievable by using url-loader.
asset/source exports the source code of the asset. Previously achievable by using raw-loader.
asset automatically chooses between exporting a data URI and emitting a separate file. Previously achievable by using url-loader with asset size limit.
To add one in you can make your config look like so:
// webpack.config.js
module.exports = {
...
module: {
rules: [
{
test: /\.(jpe?g|gif|png|svg|woff|ttf|wav|mp3)$/,
type: "asset/resource"
}
]
}
};
To control how the files get output, you can use templated paths.
In the config you can set the global template here:
// webpack.config.js
module.exports = {
...
output: {
...
assetModuleFilename: '[path][name].[hash][ext][query]'
}
}
To override for a specific set of assets, you can do this:
// webpack.config.js
module.exports = {
...
module: {
rules: [
{
test: /\.(jpe?g|gif|png|svg|woff|ttf|wav|mp3)$/,
type: "asset/resource"
generator: {
filename: '[path][name].[hash][ext][query]'
}
}
]
}
};
The provided templating will result in filenames that look like build/images/img.151cfcfa1bd74779aadb.png. The hash can be useful for cache busting etc. You should modify to your needs.

Above suggestions are good. But to try to answer your question directly I'd suggest using cpy-cli in a script defined in your package.json.
This example expects node to somewhere on your path. Install cpy-cli as a development dependency:
npm install --save-dev cpy-cli
Then create a couple of nodejs files. One to do the copy and the other to display a checkmark and message.
copy.js
#!/usr/bin/env node
var shelljs = require('shelljs');
var addCheckMark = require('./helpers/checkmark');
var path = require('path');
var cpy = path.join(__dirname, '../node_modules/cpy-cli/cli.js');
shelljs.exec(cpy + ' /static/* /build/', addCheckMark.bind(null, callback));
function callback() {
process.stdout.write(' Copied /static/* to the /build/ directory\n\n');
}
checkmark.js
var chalk = require('chalk');
/**
* Adds mark check symbol
*/
function addCheckMark(callback) {
process.stdout.write(chalk.green(' ✓'));
callback();
}
module.exports = addCheckMark;
Add the script in package.json. Assuming scripts are in <project-root>/scripts/
...
"scripts": {
"copy": "node scripts/copy.js",
...
To run the sript:
npm run copy

The way I load static images and fonts:
module: {
rules: [
....
{
test: /\.(jpe?g|png|gif|svg)$/i,
/* Exclude fonts while working with images, e.g. .svg can be both image or font. */
exclude: path.resolve(__dirname, '../src/assets/fonts'),
use: [{
loader: 'file-loader',
options: {
name: '[name].[ext]',
outputPath: 'images/'
}
}]
},
{
test: /\.(woff(2)?|ttf|eot|svg|otf)(\?v=\d+\.\d+\.\d+)?$/,
/* Exclude images while working with fonts, e.g. .svg can be both image or font. */
exclude: path.resolve(__dirname, '../src/assets/images'),
use: [{
loader: 'file-loader',
options: {
name: '[name].[ext]',
outputPath: 'fonts/'
},
}
]
}
Don't forget to install file-loader to have that working.

You can write bash in your package.json:
# package.json
{
"name": ...,
"version": ...,
"scripts": {
"build": "NODE_ENV=production npm run webpack && cp -v <this> <that> && echo ok",
...
}
}

Most likely you should use CopyWebpackPlugin which was mentioned in kevlened answer. Alternativly for some kind of files like .html or .json you can also use raw-loader or json-loader. Install it via npm install -D raw-loader and then what you only need to do is to add another loader to our webpack.config.js file.
Like:
{
test: /\.html/,
loader: 'raw'
}
Note: Restart the webpack-dev-server for any config changes to take effect.
And now you can require html files using relative paths, this makes it much easier to move folders around.
template: require('./nav.html')

I was stuck here too. copy-webpack-plugin worked for me.
However, 'copy-webpack-plugin' was not necessary in my case (i learned later).
webpack ignores root paths
example
<img src="/images/logo.png'>
Hence, to make this work without using 'copy-webpack-plugin'
use '~' in paths
<img src="~images/logo.png'>
'~' tells webpack to consider 'images' as a module
note:
you might have to add the parent directory of images directory in
resolve: {
modules: [
'parent-directory of images',
'node_modules'
]
}
Visit https://vuejs-templates.github.io/webpack/static.html

The webpack config file (in webpack 2) allows you to export a promise chain, so long as the last step returns a webpack config object. See promise configuration docs. From there:
webpack now supports returning a Promise from the configuration file. This allows to do async processing in you configuration file.
You could create a simple recursive copy function that copies your file, and only after that triggers webpack. E.g.:
module.exports = function(){
return copyTheFiles( inpath, outpath).then( result => {
return { entry: "..." } // Etc etc
} )
}

lets say all your static assets are in a folder "static" at the root level and you want copy them to the build folder maintaining the structure of subfolder, then
in your entry file) just put
//index.js or index.jsx
require.context("!!file?name=[path][name].[ext]&context=./static!../static/", true, /^\.\/.*\.*/);

In my case I used webpack for a wordpress plugin to compress js files, where the plugin files are already compressed and need to skip from the process.
optimization: {
minimize: false,
},
externals: {
"jquery": "jQuery",
},
entry: glob.sync('./js/plugin/**.js').reduce(function (obj, el) {
obj[path.parse(el).name] = el;
return obj
}, {}),
output: {
path: path.resolve(__dirname, './js/dist/plugin'),
filename: "[name].js",
clean: true,
},
That used to copy the js file as it is to the build folder. Using any other methods like file-loader and copy-webpack create issues with that.
Hope it will help someone.