We Keep Coding

Storybook webpack absolute import

In our app we are using absolute paths for import modules. We have react folder into our resolve root:
Folder structure
We are using webpack for build and develop app and it works ok, with the next options:
resolve: {
modules: [
'node_modules',
path.resolve('src')
]
},
I'm working on integration of storybook and found, that it can't find any module from this react folder.
ERROR in ./stories/index.stories.js
Module not found: Error: Can't resolve 'react/components/Button' in 'project_name/stories'
# ./stories/index.stories.js
for the next line:
import Button from 'react/components/Button';
As mark: I added resolve/modules to .storybook/webpack config and also if I try to import anything other from, for example services/xxx - it works.

Issues
react folder name conflicts with actual React package location: node_modules/react. Webpack tries to resolve to .resolution(default is node_modules) if the file does not exist in the path.
.resolution is not appropriate for this sort of usage. it is mostly used for package resolution because it can't tell source strings.
to change path selectively, use alias instead.
Solution
change your component folder's name so that it does not collide with node_modules/react. a good example is view/components/Button.
add alias to .storybook/main.js setting
// .storybook/main.js
const path = require('path');
module.exports = {
/* ... other settings goes here ... */
/**
* #param {import('webpack').Configuration} config
* */
webpackFinal: async (config, { configType }) => {
if (!config.resolve) config.resolve = {};
// this config allows to resolve `view/...` as `src/view/...`
config.resolve.alias = {
...(config.resolve.alias || {}),
view: path.resolve(__dirname, '../src/view'),
};
return config;
},
};
change storybook code in accordance with (1)
// Button.stories.jsx
import Button from 'view/components/Button';
//...

Webpack: Exposing global variable without using ProvidePlugin and expose-loader

I'm working in this ReactJS project and I have a requirement to read subfolder package.json, install them all into the node_modules and after, all dependencies installed add them to the global variable so they can be used anywhere in the code.
The problem being is that I don't have access to the jsons on expose-loader due to the syntax from webpack.config.js (I need to add them dynamically), so instead I created a loader that adding as test the package.json, gets the dependencies and tries to replicate expose-loader behaviour.
This is
var toCamelCase = function(str) {
return str.toLowerCase()
.replace( /[-_]+/g, ' ')
.replace( /[^\w\s]/g, '')
.replace( / (.)/g, function($1) { return $1.toUpperCase(); })
.replace( / /g, '' );
}
var returning_string = function(dependencies_object){
var final_string = "";
Object.keys(dependencies_object).map(function(dependency){
var location = require.resolve(dependency);
var export_dependency = 'module.exports = global["'+toCamelCase(dependency)+'"] = require("-!'+ location+'");';
final_string += export_dependency;
})
return final_string;
};
module.exports = function() {};
module.exports.pitch = function(e){
if(this.cacheable) {this.cacheable();}
var dependencies = require(e).dependencies;
return returning_string(dependencies);
};
The problem is that for some reason even though the output is exactly the same, it is not adding the library to the global context while using the expose loader it does work. When doing both things I manually added the dependency to provide plugin which I'll need to replicate later somehow anyway.
Is there any better way to do this? Or I am doing right but I am missing something?

After a research I found out the following in webpack 2.x (I am using webpack 1.x but I guess the phylosophy is valid for my version) documentation about configuration says:
write and execute function to generate a part of the configuration
So my approach to this problem is not to use a new plugin but reuse the ones that should work. Basically I wrote a new javascript file that creates all loaders that I need in a webpack.config way.
This is the file:
dependencies_loader.js
https://gist.github.com/abenitoc/b4bdc02d3c7cf287de2c92793d0a0b43
And this is aproximately the way I call it:
var webpack = require('webpack');
var dependency_loader = require('./webpack_plugins/dependencies_loader.js');
module.exports = {
devtool: 'source-map',
entry: {/* Preloading */ },
module: {preLoaders: [/*Preloading*/],
loaders: [/* Call all the loaders */].concat(dependency_loader.getExposeString()),
plugins: [
new webpack.ContextReplacementPlugin(/package\.json$/, "./plugins/"),
new webpack.HotModuleReplacementPlugin(),
new webpack.ProvidePlugin(Object.assign({
'$': 'jquery',
'jQuery': 'jquery',
'window.jQuery': 'jquery'
}, dependency_loader.getPluginProvider())), // Wraps module with variable and injects wherever it's needed
new ZipBundlePlugin() // Compile automatically zips
]
Notice that I concat the array of loaders adding the following loaders with getExposeString() that I need and reassign the object with the new global elements in pluginProvider with getPluginProvider.
Also because I use jsHint I exclude global names that's why the other method.
This only solves for node_modules dependencies, there is a different approach if you need a local library.

How to get original file path in the script with webpack?

An example code:
//in the file app.module.js
module.exports = framework.module("app", [
require('./api/api.module').name
])
//in the file app/api/api.module.js
module.exports = framework.module("app.api", [
])
Here are two dependent modules named 'app' and 'api'.
Module name is always same as file path to the module file (except module.js part, e.g. for file at app/api/api.module.js module name is 'app.api').
Is it possible to make webpack provide a filename of the included file during compilation, so following can be done?
//in the file app.module.js
module.exports = framework.module(__filename, [
require('./api/api.module').name
])
//in the file app/api/api.module.js
module.exports = framework.module(__filename, [
])
Where __filename is an actual path to the file folder.
It does not really matter what's format of name of the module, but it should be unique (for framework reasons) and lead to the module location (for debug reasons).
Update:
I've solved it for myself - this can be done by custom webpack loader which substitutes a certain placeholder with file path string. But anyway question is still open.

I know you said you resolved this yourself, yet, here's my take on it.
Your solution includes using a custom loader, however, maybe you could have solved it in a different way.
First step, in your webpack.config add these in the config object:
context: __dirname, //set the context of your app to be the project directory
node: {
__dirname: true //Allow use of __dirname in modules, based on context
},
Then, add this in your list of plugins:
new webpack.DefinePlugin({
SEPARATOR: JSON.stringify(path.sep)
})
This will replace all SEPARATOR instances in your modules with whatever the correct path separator is, for the system you are working on (you will have to require('path') in your webpack.config for this to work)
And finally in whatever module you want you can now get its name by doing
var moduleName = __dirname.replace(new RegExp(SEPARATOR, 'g'), '.');
So, for example
//in the file app.module.js
var moduleName = __dirname.replace(new RegExp(SEPARATOR, 'g'), '.');
module.exports = framework.module(moduleName, [
require('./api/api.module').name
])
//in the file app/api/api.module.js
var moduleName = __dirname.replace(new RegExp(SEPARATOR, 'g'), '.');
module.exports = framework.module(moduleName, [
])

How can I mock Webpack's require.context in Jest?

Suppose I have the following module:
var modulesReq = require.context('.', false, /\.js$/);
modulesReq.keys().forEach(function(module) {
modulesReq(module);
});
Jest complains because it doesn't know about require.context:
FAIL /foo/bar.spec.js (0s)
● Runtime Error
- TypeError: require.context is not a function
How can I mock it? I tried using setupTestFrameworkScriptFile Jest configuration but the tests can't see any changes that I've made in require.

I had the same problem, then I've made a 'solution'.
I'm pretty sure that this is not the best choice. I ended up stopping using it, by the points answered here:
https://github.com/facebookincubator/create-react-app/issues/517
https://github.com/facebook/jest/issues/2298
But if you really need it, you should include the polyfill below in every file that you call it (not on the tests file itself, because the require will be no global overridden in a Node environment).
// This condition actually should detect if it's an Node environment
if (typeof require.context === 'undefined') {
const fs = require('fs');
const path = require('path');
require.context = (base = '.', scanSubDirectories = false, regularExpression = /\.js$/) => {
const files = {};
function readDirectory(directory) {
fs.readdirSync(directory).forEach((file) => {
const fullPath = path.resolve(directory, file);
if (fs.statSync(fullPath).isDirectory()) {
if (scanSubDirectories) readDirectory(fullPath);
return;
}
if (!regularExpression.test(fullPath)) return;
files[fullPath] = true;
});
}
readDirectory(path.resolve(__dirname, base));
function Module(file) {
return require(file);
}
Module.keys = () => Object.keys(files);
return Module;
};
}
With this function, you don't need to change any require.context call, it will execute with the same behavior as it would (if it's on webpack it will just use the original implementation, and if it's inside Jest execution, with the polyfill function).

After spending some hours trying each of the answers above. I would like to contribute.
Adding babel-plugin-transform-require-context plugin to .babelrc for test env fixed all the issues.
Install - babel-plugin-transform-require-context here https://www.npmjs.com/package/babel-plugin-transform-require-context (available with yarn too)
Now add plugin to .babelrc
{
"env": {
"test": {
"plugins": ["transform-require-context"]
}
}
}
It will simply transform require-context for test env into dummy fn calls so that code can run safely.

If you are using Babel, look at babel-plugin-require-context-hook. Configuration instructions for Storybook are available at Storyshots | Configure Jest to work with Webpack's require.context(), but they are not Storyshots/Storybook specific.
To summarise:
Install the plugin.
yarn add babel-plugin-require-context-hook --dev
Create a file .jest/register-context.js with the following contents:
import registerRequireContextHook from 'babel-plugin-require-context-hook/register';
registerRequireContextHook();
Configure Jest (the file depends on where you are storing your Jest configuration, e.g. package.json):
setupFiles: ['<rootDir>/.jest/register-context.js']
Add the plugin to .babelrc
{
"presets": ["..."],
"plugins": ["..."],
"env": {
"test": {
"plugins": ["require-context-hook"]
}
}
}
Alternatively, add it to babel.config.js:
module.exports = function(api) {
api.cache(true)
const presets = [...]
const plugins = [...]
if (process.env.NODE_ENV === "test") {
plugins.push("require-context-hook")
}
return {
presets,
plugins
}
}
It may be worth noting that using babel.config.js rather than .babelrc may cause issues. For example, I found that when I defined the require-context-hook plugin in babel.config.js:
Jest 22 didn't pick it up;
Jest 23 picked it up; but
jest --coverage didn't pick it up (perhaps Istanbul isn't up to speed with Babel 7?).
In all cases, a .babelrc configuration was fine.
Remarks on Edmundo Rodrigues's answer
This babel-plugin-require-context-hook plugin uses code that is similar to Edmundo Rodrigues's answer here. Props to Edmundo! Because the plugin is implemented as a Babel plugin, it avoids static analysis issues. e.g. With Edmundo's solution, Webpack warns:
Critical dependency: require function is used in a way in which dependencies cannot be statically extracted
Despite the warnings, Edmundo's solution is the most robust because it doesn't depend on Babel.

Extract the call to a separate module:
// src/js/lib/bundle-loader.js
/* istanbul ignore next */
module.exports = require.context('bundle-loader?lazy!../components/', false, /.*\.vue$/)
Use the new module in the module where you extracted it from:
// src/js/lib/loader.js
const loadModule = require('lib/bundle-loader')
Create a mock for the newly created bundle-loader module:
// test/unit/specs/__mocks__/lib/bundle-loader.js
export default () => () => 'foobar'
Use the mock in your test:
// test/unit/specs/lib/loader.spec.js
jest.mock('lib/bundle-loader')
import Loader from 'lib/loader'
describe('lib/loader', () => {
describe('Loader', () => {
it('should load', () => {
const loader = new Loader('[data-module]')
expect(loader).toBeInstanceOf(Loader)
})
})
})

Alrighty! I had major issues with this and managed to come to a solution that worked for me by using a combination of other answers and the Docs. (Took me a good day though)
For anyone else who is struggling:
Create a file called bundle-loader.js and add something like:
module.exports = {
importFiles: () => {
const r = require.context(<your_path_to_your_files>)
<your_processing>
return <your_processed_files>
}
}
In your code import like:
import bundleLoader from '<your_relative_Path>/bundle-loader'
Use like
let <your_var_name> = bundleLoader.importFiles()
In your test file right underneath other imports:
jest.mock('../../utils/bundle-loader', () => ({
importFiles: () => {
return <this_will_be_what_you_recieve_in_the_test_from_import_files>
}
}))

Installing
babel-plugin-transform-require-context
package and adding the plugin in the .babelrc resolved the issue for me.
Refer to the documentation here:
https://www.npmjs.com/package/babel-plugin-transform-require-context

The easiest and fastest way to solve this problem will be to install require-context.macro
npm install --save-dev require-context.macro
then just replace:
var modulesReq = require.context('.', false, /\.js$/);
with:
var modulesReq = requireContext('.', false, /\.js$/);
Thats it, you should be good to go!
Cheers and good luck!

Implementation problems not mentioned:
Jest prevents out-of-scope variables in mock, like __dirname.
Create React App limits Babel and Jest customization. You need to use src/setupTests.js which is run before every test.
fs is not supported in the browser. You will need something like browserFS. Now your app has file system support, just for dev.
Potential race condition. Export after this import. One of your require.context imports includes that export. I'm sure require takes care of this, but now we are adding a lot of fs work on top of it.
Type checking.
Either #4 or #5 created undefined errors. Type out the imports, no more errors. No more concerns about what can or can't be imported and where.
Motivation for all this? Extensibility. Keeping future modifications limited to one new file. Publishing separate modules is a better approach.
If there's an easier way to import, node would do it. Also this smacks of premature optimization. You end up scrapping everything anyways because you're now using an industry leading platform or utility.

If you're using Jest with test-utils in Vue.
Install these packages:
#vue/cli-plugin-babel
and
babel-plugin-transform-require-context
Then define babel.config.js at the root of the project with this configuration:
module.exports = function(api) {
api.cache(true);
const presets = [
'#vue/cli-plugin-babel/preset'
];
const plugins = [];
if (process.env.NODE_ENV === 'test') {
plugins.push('transform-require-context');
}
return {
presets,
plugins
};
};
This will check if the current process is initiated by Jest and if so, it mocks all the require.context calls.

I faced the same issue with an ejected create-react-app project
and no one from the answers above helped me...
My solution were to copy to config/babelTransform.js the follwoing:
module.exports = babelJest.createTransformer({
presets: [
[
require.resolve('babel-preset-react-app'),
{
runtime: hasJsxRuntime ? 'automatic' : 'classic',
},
],
],
plugins:["transform-require-context"],
babelrc: false,
configFile: false,
});

Simpleset Solution for this
Just Do
var modulesReq = require.context && require.context('.', false, /\.js$/);
if(modulesReq) {
modulesReq.keys().forEach(function(module) {
modulesReq(module);
});
}
So Here I have added extra check if require.context is defined then only execute By Doing this jest will no longer complain

Relative paths with RequireJS modules/packages

I'm fairly new to RequireJS and I've run into a bit of a problem. I've written a little framework built on Backbone using RequireJS and I want it to be re-usable in different projects. So, with some searching I learned that require allows packages. This seemed like what I was looking for. I have a main.js file to launch my app that essentially looks like this:
require.config({
packages: ['framework']
});
require(['framework'], function(framework) {
framework.createDash();
});
Then in the same directory as my main.js I have another directory called "framework" which contains another main.js which looks like this:
define(function(require, exports, module) {
exports.createDash = function(dash, element) {
require(['dash/dash.model', 'dash/dash.view'], function(DashModel, DashView) {
return new DashView({
model: new DashModel(dash),
el: element ? element : window
});
});
};
});
In searching I found this page which indicates that the 'require' argument should be scoped to the submodule. However, when I try to require things they are still relative to my original main.js. I've tried a number of things and searched for hours to no avail. Is there any way I can have my require/define calls within my package included relative to the main.js in it's root?

You need to define your submodule as package in the require configuration:
require.config({
packages: [
{ name: 'packagename',
location: 'path/to/your/package/root', // default 'packagename'
main: 'scriptfileToLoad' // default 'main'
}]
... some other stuff ...
});
To load your module you just need to use your 'packagename' at the requirements:
define(['jquery', 'packagename'], function($, MyPackage) {
MyPackage.useIt()
});
In your package you must use the ./ prefix to load your files relative to your submodule:
define(['globalDependency', './myLocalFile'], function(Asdf, LocalFile) {
LocalFile.finallyLoaded();
});
There is a useful shortcut: If your package name equals to your location and your main file is called 'main.js', then you can replace this
packages: [
{ name: 'packagename',
location: 'packagename',
main: 'main'
}]
to this:
packages: ['packagename']
As far as I can see, you already tried to define a package but did you also use the ./ prefix? Without this prefix require will try to find the files in it's global root-path. And without a package, ./ will be useless because the relative path is the same as the global root-path.
Cheers

I figured out the answer to my question, and the solution (they were not the same apparently). I guess I'll post it here in case it can help someone else in the future.
Essentially what I was wanting was to load my framework within its own context. I found the context option under the configuration section on require's website and an example of how to use it. Originally I tried this by doing something like:
var req = require.config({
baseUrl: 'framework',
context: 'framework',
paths: {
jQuery: 'lib/jquery/jquery-1.7.min.js',
Underscore: 'lib/underscore/underscore.min.js',
Backbone: 'lib/backbone/backbone.min.js',
etc...
}
});
req(['main'], function() {});
There were two problems with this. First, my 'req' variable was being defined outside of the framework, but I wanted the framework to define it's own paths. And second, whenever a file outside of the framework would require a file within the framework, which would in turn require 'jQuery', for example, then jQuery (or whatever else) wouldn't be required from within the context of the framework instance of require and so it couldn't find the file.
What I ended up doing was defining my framework's main.js to look something like this:
var paths = {
jQuery: 'lib/jquery/jquery-1.7.min.js',
Underscore: 'lib/underscore/underscore.min.js',
Backbone: 'lib/backbone/backbone.min.js',
etc...
};
define(function() {
var exports = {};
exports.initialize = function(baseUrl, overridePaths, callback) {
if(!overridePaths) {
overridePaths = {};
}
if(baseUrl && baseUrl[baseUrl.length - 1] != '/') {
baseUrl = baseUrl + '/';
}
var fullpaths = {};
for(var path in paths) {
// Don't add baseUrl to anything that looks like a full URL like 'http://...' or anything that begins with a forward slash
if(paths[path].match(/^(?:.*:\/\/|\/)/)) {
fullpaths[path] = paths[path];
}
else {
fullpaths[path] = baseUrl + paths[path];
}
}
var config = {paths: fullpaths};
for(var pathName in overridePaths) {
config.paths[pathName] = overridePaths[pathName];
}
require.config(config);
// Do anything else you need to do such as defining more functions for exports
if(callback) {
callback();
}
}
return exports;
});
And then in my project's main.js file I just do this:
require(['framework/main'], function(framework) {
// NOTE: This setTimeout() call is used because, for whatever reason, if you make
// a 'require' call in here or in the framework without it, it will just hang
// and never actually go fetch the files in the browser. There's probably a
// better way to handle this, but I don't know what it is.
setTimeout(function() {
framework.initialize('framework', null, function() {
// Do stuff here
}
}, 0);
});
This takes whatever is passed in to the framework's initialize() method for 'baseURL' and prepends that to any paths that the framework defines that do not start with a forward slash or 'anything://', unless they are override paths. This allows the package using the framework to override things like 'jQuery'.

This worked for me, adding a "./" prefix to the module names:
define(function (require, exports, module) {
exports.createDash = function (dash, element) {
require([ './dash/dash.model', './dash/dash.view' ], function (DashModel, DashView) {
return new DashView({
model : new DashModel(dash),
el : element ? element : window
});
});
};
});

A process that worked well for me for allowing a package with submodules to be used directly from data-main or from an outside framework, assuming that a main.js (or other package main) is called by a particular name, was to use var baseUrl = require.toUrl('packageName') + '/../' as a prefix to a require.config({ paths: { ... } }) configuration file. For instance:
var music21Base = require.toUrl('music21') + '/../';
require.config({ paths: {
'jquery': music21Base + 'ext/jquery/jquery.2.1.10.min';
'subModuleLoader': music21Base + 'src/subModuleLoader';
} });
The setting of context: "xxx" worked fine for calling normal modules with ./modName but did not work for the paths argument for me.