Develop Reference

Modify build path of assets in Vite/Rollup?

Let's say I have this folder structure:
parent
|-parent.html
|-parent.js
|-child
|--child.html
|--child.js
I want them to output in the same structure in my dist folder.
By default this is what gets output:
dist/assets/parent.js
dist/assets/child.js
I want them to output like this:
dist/parent/parent.js
dist/parent/child/child.js
I tried changing the assetFileNames option of Rollup but it didn't do anything.

The output filenames are configured in Rollup with build.rollupOptions. Set output.entryFileNames to configure the location of the entry .js files to match their original directory structure:
// vite.config.js
import { fileURLToPath } from 'url';
import { defineConfig } from 'vite';
import path from 'path';
const rootDir = fileURLToPath(new URL('.', import.meta.url));
export default defineConfig({
build: {
rollupOptions: {
input: {
parent: './parent/parent.html',
child: './parent/child/child.html',
},
output: {
entryFileNames: (assetInfo) => {
// assetInfo.facadeModuleId contains the file's full path
if (assetInfo.facadeModuleId) {
const assetPath = path.dirname(assetInfo.facadeModuleId).replace(rootDir, '');
return assetPath + '/[name]-[hash].js';
} else {
return 'assets/js/[name]-[hash].js';
}
},
},
},
},
});
demo
Notes
Assets (such as .css files) and shared modules (vendor .js chunks) cannot be redirected with the solution above because the asset info from the related hooks do not provide the file's full path.
In a vanilla Rollup project, output.preserveModules=true would've accomplished the original goal, but that option conflicts with Vite's own settings for Rollup.

NextJS: Can't use absolute imports in external libraries when using experimental.externalDir

Having the following folder structure of my monorepo that uses nextjs, lerna and npm workspaces:
packages
next-js-app
pages
index.tsx
tsconfig.json
ui-library
src
components
dropdown.tsx
index.ts
utils.ts
tsconfig.json
package.json
lerna.json
tsconfig.json
I want to import the ui-library in the next-js-app such as:
// packages/next-js-app/pages/index.tsx
import { UiLibrary } from '#workspaceName/ui-library'
I allowed it by adding externalDir: true to experimental key in the next.config.js inside the next-js-app:
module.exports = {
...
experimental: {
externalDir: true
}
...
}
Problem
The import works, but inside the packages/ui-library/src/components/dropdown.tsx there's a line:
// packages/ui-library/src/components/dropdown.tsx
import { helperFunction } from 'utils'
meaning that I want to import helperFunction from packages/ui-library/src/utils.ts.
When running next dev script from packages/next-js-app I get the following error:
wait - compiling...
error - ../ui-library/src/components/dropdown.tsx:3:0
Module not found: Can't resolve 'utils'
1 | ...
2 | ...
> 3 | import { helperFunction } from "utils"
4 |
5 | const Dropdown = () => {
6 | const onClick = (event) => {
While if I run the ui-library separately it will be ok with using absolute paths in imports.
Question
How can I make absolute imports work in this case?

The way I fixed it in my case, was adding aliases to my webpack config (inside next.config.js file)
module.exports = {
...
experimental: {
externalDir: true
}
config.resolve = {
...config.resolve,
alias: {
...config.resolve.alias,
'utils': path.resolve('../../packages/ui-library/src/utils'),
// ^ defined all paths used within my external UI library
},
}
}

Yarn Workspaces, workspace does not emit errors or warnings

I have followed the following post in order to create a monorepo using yarn workspaces and craco.
It works really well except one thing: the errors/warnings of the common (components )library are not emitted to the console.
The structure is very simple:
monorepo
|-packages
|-components
|-fe
Fe is the main webApp that uses the components library.
The FE emits all warnings correctly, components does not.
How to make the shared component emit warnings/errors?
Updated:
Steps to reproduce in this repo:
https://github.com/sofoklisM/my-monorepo.git

What you need to change is the context option of the underlying ESLint Webpack plugin that is used by Create React App.
In this case I changed the context of ESLint to the root of the monorepo (yarn workspace root).
Here is an updated craco.config.js that should do the trick:
// craco.config.js
const path = require("path");
const { getLoader, loaderByName } = require("#craco/craco");
const { getPlugin, pluginByName } = require("#craco/craco/lib/webpack-plugins")
const absolutePath = path.join(__dirname, "../components");
module.exports = {
webpack: {
alias: {},
plugins: [],
configure: (webpackConfig, { env, paths }) => {
const { isFound, match } = getLoader(
webpackConfig,
loaderByName("babel-loader")
);
if (isFound) {
const include = Array.isArray(match.loader.include)
? match.loader.include
: [match.loader.include];
match.loader.include = include.concat([absolutePath]);
}
// Change context of ESLint Webpack Plugin
const { match: eslintPlugin } = getPlugin(webpackConfig, pluginByName("ESLintWebpackPlugin"));
eslintPlugin.options['context'] = path.join(__dirname, "../..");
return webpackConfig;
}
}
};
I've also made an updated fork of your reproduction repo here: https://github.com/ofhouse/stackoverflow-65447779

How to get babel-node to convert files referenced by Workers to commonjs? (like babel does)

In an Express.js app, I'm using Babel to precompile to commonjs before starting it. The compilation step looks like this:
babel ./src --out-dir dist
node ./dist/bin
As part of the project I have a file called my-worker.js where I use import syntax:
# my-worker.js
import { parentPort, workerData } from 'worker_threads'
import axios from 'axios'
...
And that is used by other-file.js:
#other-file.js
...
const worker = new Worker(__dirname + '/my-worker.js', { workerData: ... })
...
This works fine. Babel converts all the files to commonjs, and loading the worker script works.
BUT
When I use #babel/node, this doesn't work:
babel-node ./src/bin
I get the warning:
(node:4865) Warning: To load an ES module, set "type": "module" in the package.json or use the .mjs extension.
Along with the error:
Cannot use import statement outside a module
I don't want to use "type": "module", since then I have to explicitly name file extensions, and also I'm not sure that import X, { y } from ... syntax is supported (which I like).
If I change my worker file to be my-worker.mjs, and change the new Worker statement accordingly, then that works with #babel/node, but not with my production build since filenames are changed back to .js.
How can I get #babel/node to load and cache (I guess this is what it needs to do?) files loaded by a Worker? Why does this work with #babel and not with #babel/node?
My .babelrc file looks like this:
{
"presets": [
[
"#babel/preset-env",
{
"useBuiltIns": "usage",
"corejs": 3,
"targets": {
"node": "13"
},
"modules": "commonjs"
}
]
]
}

The #babel/register API can help dynamically transpile a script source, as pointed out in https://github.com/babel/babel/issues/10972#issuecomment-572608142
You can use this approach with eval mode to make a single-file script. This might be useful if you use babel-node to run a command-line utility script.
import { isMainThread, Worker, workerData } from "worker_threads";
function createTranspiledWorker(filename, options) {
const transpile = `
require('#babel/register');
require(${JSON.stringify(filename)});
`;
return new Worker(transpile, { ...options, eval: true });
}
async function main() {
const w = createTranspiledWorker(__filename, { workerData: { hello: "world" } });
const exit = new Promise(resolve => w.on("exit", resolve));
await exit;
}
function worker() {
console.log("worker", workerData);
}
if (isMainThread) {
main();
} else {
worker();
}

Specify code to run before any Jest setup happens

The tl;dr is:
1) How can I have Jest use the native require function to load all modules in my tests anywhere.
2) Where / how would I go about modifying (ie replacing with the esm loader) https://github.com/standard-things/esm the require function in one place, before any tests run, so all tests will use the modified require.
I'd like to use the esm-loader with my Jest test files. In order to do so, I need to patch the require function globally, before any test code runs, with something like
require = require("#std/esm")(module, { esm: "js", cjs: true });
How do I tell Jest to execute that code before anything else is touched or requested?
I tried pointing both setupTestFrameworkScriptFile and an setupFiles array entry to a file with that in it, but neither worked (though I did confirm that both ran).
Alternatively, I'm firing off these tests with an npm script
"scripts": {
"test": "jest"
}
Is there some CLI magic whereby I can just load a module and then run jest?
Edit - the testEnvironment and resolver options make me wonder if this is ever even using the actual Node require function to load modules, or instead using its own module loader. If so I wonder if this is even possible.

So this one was a bit tough to get working. The solution is quite simple but it took me a while to get it working. The problem is that whenever you use any module in jest
Setup Files
Setup Framework Files
Test Files
Module files
They are all loaded in below way
({"Object.":function(module,exports,require,__dirname,__filename,global,jest){/*Module code inside*/
}});
If you have a look at node_modules/jest-runtime/build/index.js:495:510
const dirname = (_path || _load_path()).default.dirname(filename);
localModule.children = [];
localModule.parent = mockParentModule;
localModule.paths = this._resolver.getModulePaths(dirname);
localModule.require = this._createRequireImplementation(filename, options);
const transformedFile = this._scriptTransformer.transform(
filename,
{
collectCoverage: this._coverageOptions.collectCoverage,
collectCoverageFrom: this._coverageOptions.collectCoverageFrom,
collectCoverageOnlyFrom: this._coverageOptions.collectCoverageOnlyFrom,
isInternalModule,
mapCoverage: this._coverageOptions.mapCoverage },
this._cacheFS[filename]);
this._createRequireImplementation(filename, options); gives every module a custom require object. So you as such don't get the native require function at all, anywhere. Once jest has started every module loaded from then on will have jest's custom require function.
When we load a module, the requireModule methods from the jest-runtime gets called. Below is an excerpt from the same
moduleRegistry[modulePath] = localModule;
if ((_path || _load_path()).default.extname(modulePath) === '.json') {
localModule.exports = this._environment.global.JSON.parse(
(0, (_stripBom || _load_stripBom()).default)((_gracefulFs || _load_gracefulFs()).default.readFileSync(modulePath, 'utf8')));
} else if ((_path || _load_path()).default.extname(modulePath) === '.node') {
// $FlowFixMe
localModule.exports = require(modulePath);
} else {
this._execModule(localModule, options);
}
As you can see if the extension of the file is .node it loads the module directly, else it calls the _execModule. This function is the same code that I posted earlier which does the code transformation
const isInternalModule = !!(options && options.isInternalModule);
const filename = localModule.filename;
const lastExecutingModulePath = this._currentlyExecutingModulePath;
this._currentlyExecutingModulePath = filename;
const origCurrExecutingManualMock = this._isCurrentlyExecutingManualMock;
this._isCurrentlyExecutingManualMock = filename;
const dirname = (_path || _load_path()).default.dirname(filename);
localModule.children = [];
localModule.parent = mockParentModule;
localModule.paths = this._resolver.getModulePaths(dirname);
localModule.require = this._createRequireImplementation(filename, options);
Now when we want to modify require function for our test, we need _execModule to export our code directly. So the code should be similar to loading of a .node modules
} else if ((_path || _load_path()).default.extname(modulePath) === '.mjs') {
// $FlowFixMe
require = require("#std/esm")(localModule);
localModule.exports = require(modulePath);
} else {
But doing that would mean patching the code, which we want to avoid. So what we do instead is avoid using the jest command directly, and create our own jestload.js and running that. The code for loading jest is simple
#!/usr/bin/env node
/**
* Copyright (c) 2014-present, Facebook, Inc. All rights reserved.
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of this source tree.
*/
cli = require('jest/bin/jest');
Now we want to modify the _execModule before the cli loads. So we add below code
const jestRuntime = require("jest-runtime");
oldexecModule = jestRuntime.prototype._execModule;
jestRuntime.prototype._execModule = function (localModule, options) {
if (localModule.id.indexOf(".mjs") > 0) {
localModule.exports = require("#std/esm")(localModule)(localModule.id);
return localModule;
}
return oldexecModule.apply(this, [localModule, options]);
};
cli = require('jest/bin/jest');
Now time for a test
//__test__/sum.test.js
sum = require('../sum.mjs').sum;
test('adds 1 + 2 to equal 3', () => {
expect(sum(1, 2)).toBe(3);
});
test('adds 2 + 3 to equal 5', () => {
expect(sum(3, 2)).toBe(5);
});
And a sum.mjs file
export function sum (x, y) { return x + y }
Now we run the test
The solution is available on below repo
https://github.com/tarunlalwani/jest-overriding-require-function-stackoverflow
You can clone and test the solution by running npm test.

setupFiles worked for me. Add this in package.json:
"jest": {
"setupFiles": ["./my_file.js"]
},
https://jestjs.io/docs/en/configuration.html#setupfiles-array

I tried using node -r #std/esm run.js where run.js is just a script that calls jest, but it does not work and crashes here : https://github.com/facebook/jest/blob/master/packages/jest-runtime/src/script_transformer.js#L305.
From what I understand from this line means that it is not possible because jest compiles the module using the native vm module. The above lines (290):
if (willTransform) {
const transformedSource = this.transformSource(
filename,
content,
instrument,
!!(options && options.mapCoverage));
wrappedCode = wrap(transformedSource.code);
sourceMapPath = transformedSource.sourceMapPath;
} else {
is the code called when you are specifying transforms in your jest config.
Conclusion : until esm are supported ( and they will be under the .mjs extension ) you cannot import es modules in jest without specifying a transform. You could try to monkey patch vm but I would really advise against this option.
Specifying a jest transform is really not that hard, and for es modules it's really as simple as using babel-jest with the right babel config :
Below a package.json with minimal settings
{
"dependencies": {
"babel-jest": "^21.2.0",
"babel-plugin-transform-es2015-modules-commonjs": "^6.26.0",
"jest": "^21.2.1"
},
"jest": {
"testMatch": [
"<rootDir>/src/**/__tests__/**/*.js?(x)",
"<rootDir>/src/**/?(*.)(spec|test).js?(x)"
],
"transform": {
"^.+\\.(js|jsx)$": "<rootDir>/node_modules/babel-jest"
},
"testEnvironment": "node",
"testURL": "http://localhost",
"moduleFileExtensions": [
"js",
"json"
]
},
"babel": {
"plugins": ["babel-plugin-transform-es2015-modules-commonjs"]
}
}