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Bundle multiple named AMD modules with dependencies into one JS file (building a web app extension system)

I'm working on an extension system for my web app. Third-party developers should be able to extend the app by providing named AMD modules exporting constants and functions following a predefined spec and bundled into a single .js JavaScript file.
Example JavaScript bundle:
define('module1', ['exports', 'module3'], (function (exports, module3) {
exports.spec = 'http://example.com/spec/extension/v1'
exports.onRequest = function (request) { return module3.respond('Hello, World.') }
}));
define('module2', ['exports', 'module3'], (function (exports, module3) {
exports.spec = 'http://example.com/spec/extension/v1'
exports.onRequest = function (request) { return module3.respond('Foo. Bar.') }
}));
define('module3', ['exports'], (function (exports) {
exports.respond = function (message) { return { type: 'message', message: message } }
}));
In the above example module1 and module2 are extension modules (identified by the spec export) and module3 is a shared dependency (e.g. coming from an NPM package). Extension bundles will be loaded in a worker within a sandboxed iframe to seal of the untrusted code in the browser.
Example TypeScript source:
// module1.ts
import respond from 'module3'
export const spec = 'http://example.com/spec/extension/v1'
export const onRequest = (request: Request): Response => respond('Hello, World.')
// module2.ts
import respond from 'module3'
export const spec = 'http://example.com/spec/extension/v1'
export const onRequest = (request: Request): Response => respond('Foo. Bar.')
// module3.ts
import dep from 'some-npm-package'
export respond = (message: string) => dep.createMessageObject(message)
Here is my list of requirements to bundling:
All necessary dependencies (e.g. shared module, NPM package logic) must be included in the bundle
The source code needs to be transpiled to browser compatible code if necessary
The AMD format is required by the custom extension loader implementation
The AMD modules must not be anonymous as the module file names are lost while bundling
No relative paths must be used among dependencies (e.g. ./path/to/module3 instead of module3)
The result should be one JavaScript bundle, thus ONE JavaScript file and ONE sourcemaps file
What's the easiest way to do this?
This is the closest solution I found using rollup and the following rollup.config.js:
import { nodeResolve } from '#rollup/plugin-node-resolve'
import { terser } from 'rollup-plugin-terser'
import typescript from '#rollup/plugin-typescript'
export default {
input: [
'src/module1.ts',
'src/module2.ts'
],
output: {
dir: 'dist',
format: 'amd',
sourcemap: true,
amd: {
autoId: true
}
},
plugins: [
typescript(),
nodeResolve(),
terser()
]
}
From this I get the desired named AMD modules (one for each entry point and chunk) in separate .js files. Problems:
Some dependencies are referenced by ./module3 while being named module3.
The modules appear in separate JavaScript and Sourcemap files instead of being concatenated into a single bundle.
Questions:
Is there an easy fix to the above rollup.config.js config to solve the problem?
I tried to write a small rollup plugin but I failed to get the final AMD module code within it to concatenate it to a bundle. Only the transpiled code is available to me. In addition I don't know how to handle sourcemaps during concatenation.
Is there an alternative to rollup better suited to this bundling scenario?
The big picture: Am I completely on the wrong track when it comes to building an extension system? Is AMD the wrong choice?

I found a way to extend the rollup.config.js mentioned in the question with a custom concatChunks rollup plugin to bundle multiple AMD chunks within a single file and having the source maps rendered, too. The only issue I didn't find an answer to was the relative module names that kept popping up. However, this may be resolved in the AMD loader.
Here's the full rollup.config.js that worked for me:
import Concat from 'concat-with-sourcemaps'
import glob from 'glob'
import typescript from '#rollup/plugin-typescript'
import { nodeResolve } from '#rollup/plugin-node-resolve'
import { terser } from 'rollup-plugin-terser'
const concatChunks = (
fileName = 'bundle.js',
sourceMapFileName = 'bundle.js.map'
) => {
return {
name: 'rollup-plugin-concat-chunks',
generateBundle: function (options, bundle, isWrite) {
const concat = new Concat(true, fileName, '\n')
// Go through each chunk in the bundle
let hasSourceMaps = false
Object.keys(bundle).forEach(fileId => {
const fileInfo = bundle[fileId]
if (fileInfo.type === 'chunk') {
let hasSourceMap = fileInfo.map !== null
hasSourceMaps = hasSourceMaps || hasSourceMap
// Concat file content and source maps with bundle
concat.add(
fileInfo.fileName,
fileInfo.code,
hasSourceMap ? JSON.stringify(fileInfo.map) : null
)
// Prevent single chunks from being emitted
delete bundle[fileId]
}
})
// Emit concatenated chunks
this.emitFile({
type: 'asset',
name: fileName,
fileName: fileName,
source: concat.content
})
// Emit concatenated source maps, if any
if (hasSourceMaps) {
this.emitFile({
type: 'asset',
name: sourceMapFileName,
fileName: sourceMapFileName,
source: concat.sourceMap
})
}
}
}
}
export default {
input: glob.sync('./src/*.{ts,js}'),
output: {
dir: 'dist',
format: 'amd',
sourcemap: true,
amd: {
autoId: true
}
},
plugins: [
typescript(),
nodeResolve(),
terser(),
concatChunks()
]
}
Please make sure you npm install the dependencies referenced in the import statements to make this work.
Considering the big picture, i.e. the extension system itself, I am moving away from a "one AMD module equals one extension/contribution" approach, as current developer tools and JavaScript bundlers are not ready for that (as this question shows). I'll go with an approach similar to the Visual Studio Code Extension API and will use a single "default" module with an activate export to register contributions a bundle has to offer. I hope that this will make extension bundling an easy task no matter what tools or languages are being used.

How to redirect pages/app folder to subdomain in next.js

I search a lot for this on the internet but I don't find any article related to it.
Like I have a folder called pages in the root of my project and below tree is files of it.
| 404.js
| auth.js
| index.js
| _app.js
| _error.js
\---app
index.js
next.js gives default behavior when someone opens project.local:3000 it will openindex.js and project.local:3000/app it will open app/index.js but I want that when someone open app.project.local:3000 it will open app/index.js.
My Hosts file
127.0.0.1 project.local
127.0.0.1 app.project.local
In short
I want to redirect pages/app folder to app.project.local or app.example.com in next.js

Most updated solution
I found the solution while exploring the documentation on redirects.
In your Next.js's root folder, create a vercel.json file and then insert your redirects as object inside redirects array like so:
{
"redirects": [
{ "source": "/blog", "destination": "https://blog.example.com" }
]
}
This will only work on production environment. It should work as intended.

I'm still a noobie in next.js (2nd day learning), but I was searching for subdomain support and I found three solutions on this Github issue: https://github.com/vercel/next.js/issues/5682
Using zones (still no idea how it works)
"Vercel will implement subdomain routing in the near future" (I don't expect to use Vercel in the near future)
(my preferred, but not yet tested) An example using custom servers in Next.js: https://github.com/dcangulo/nextjs-subdomain-example
For #3, see how it was implemented in the server.js file

With the new "middleware" feature of Next.js, you can rewrite it using a function instead of the rewrite object and keep the getStaticProps working.
// middleware.ts
import { NextResponse } from 'next/server';
import type { NextRequest } from 'next/server';
import { getValidSubdomain } from '#/utils/subdomain';
// RegExp for public files
const PUBLIC_FILE = /\.(.*)$/; // Files
export async function middleware(req: NextRequest) {
// Clone the URL
const url = req.nextUrl.clone();
// Skip public files
if (PUBLIC_FILE.test(url.pathname) || url.pathname.includes('_next')) return;
const host = req.headers.get('host');
const subdomain = getValidSubdomain(host);
if (subdomain) {
// Subdomain available, rewriting
console.log(`>>> Rewriting: ${url.pathname} to /${subdomain}${url.pathname}`);
url.pathname = `/${subdomain}${url.pathname}`;
}
return NextResponse.rewrite(url);
}
You can take a look on nextjs docs about middleware and I've also wrote this medium article with some related content that might help.

NextJS now supports Locales: https://nextjs.org/docs/advanced-features/i18n-routing.
You can specify a locale in your config, e.g. admin and specify the URL like this:
// next.config.js
module.exports = {
i18n: {
// These are all the locales you want to support in
// your application
locales: ['en-US', 'admin', 'nl-NL'],
// This is the default locale you want to be used when visiting
// a non-locale prefixed path e.g. `/hello`
defaultLocale: 'en-US',
// This is a list of locale domains and the default locale they
// should handle (these are only required when setting up domain routing)
// Note: subdomains must be included in the domain value to be matched e.g. "fr.example.com".
domains: [
{
domain: 'example.com',
defaultLocale: 'en-US',
},
{
domain: 'example.nl',
defaultLocale: 'nl-NL',
},
{
domain: 'admin.example.com',
defaultLocale: 'admin',
// an optional http field can also be used to test
// locale domains locally with http instead of https
http: true,
},
],
},
}

Web workers inside a JS library with Rollup

I am building a negamax engine in Typescript that uses Thread.js web-workers. It is a npm library that will be imported by an application built using webpack.
I am using Rollup to build the engine - how can I export the web-worker files so they are copied into the client's build directory as a separate chunk?

There are plugins for that: Alorel/rollup-plugin-web-worker, darionco/rollup-plugin-web-worker-loader
..but I ended up doing it by scratch, using a separate build configuration for the worker(s). This simply gives me more control over the situation.
Attached is the rollup.config.worker.js that I use.
The main rollup.config.mjs imports this file, has its configuration as the first build configuration. The real build config uses #rollup/plugin-replace to inject the worker's hash to the code loading it.
/*
* Rollup config for building web worker(s)
*
* Imported by the main rollup config.
*/
import sizes from '#atomico/rollup-plugin-sizes'
import resolve from '#rollup/plugin-node-resolve'
import replace from '#rollup/plugin-replace'
import { terser } from 'rollup-plugin-terser'
import {dirname} from 'path'
import {fileURLToPath} from 'url'
const myPath = dirname(fileURLToPath(import.meta.url));
const watch = process.env.ROLLUP_WATCH;
const REGION = process.env.REGION;
if (!REGION) throw new Error("'REGION' env.var. not provided");
let loggingAdapterProxyHash;
const catchHashPlugin = {
name: 'my-plugin',
// Below, one can define hooks for various stages of the build.
//
generateBundle(_ /*options*/, bundle) {
Object.keys(bundle).forEach( fileName => {
// filename: "proxy.worker-520aaa52.js"
//
const [_,c1] = fileName.match(/^proxy.worker-([a-f0-9]+)\.js$/) || [];
if (c1) {
loggingAdapterProxyHash = c1;
return;
}
console.warn("Unexpected bundle generated:", fileName);
});
}
};
const pluginsWorker = [
resolve({
mainFields: ["esm2017", "module"],
modulesOnly: true // "inspect resolved files to assert that they are ES2015 modules"
}),
replace({
'env.REGION': JSON.stringify(REGION),
//
preventAssignment: true // to mitigate a console warning (Rollup 2.44.0); remove with 2.45?
}),
//!watch && terser(),
catchHashPlugin,
!watch && sizes(),
];
const configWorker = {
input: './adapters/logging/proxy.worker.js',
output: {
dir: myPath + '/out/worker', // under which 'proxy.worker-{hash}.js' (including imports, tree-shaken-not-stirred)
format: 'es', // "required"
entryFileNames: '[name]-[hash].js', // .."chunks created from entry points"; default is: '[name].js'
sourcemap: true, // have source map even for production
},
plugins: pluginsWorker
}
export default configWorker;
export { loggingAdapterProxyHash }
Using in main config:
replace({
'env.PROXY_WORKER_HASH': () => {
const hash= loggingAdapterProxyHash;
assert(hash, "Worker hash not available, yet!");
return JSON.stringify(hash);
},
//
preventAssignment: true // to mitigate a console warning (Rollup 2.44.0); remove with 2.45?
}),
..and in the Worker-loading code:
const PROXY_WORKER_HASH = env.PROXY_WORKER_HASH; // injected by Rollup build
...
new Worker(`/workers/proxy.worker-${PROXY_WORKER_HASH}.js?...`);
If anyone wants to get a link to the whole repo, leave a message and I'll post it there. It's still in flux.
Edit:
After writing the answer I came across this: Building module web workers for cross browser compatibility with rollup (blog, Jul 2020)
TL;DR If you wish to use EcmaScript Modules for the worker, watch out! Firefox and Safari don't have the support, as of today. source And the Worker constructor needs to be told that the worker source is ESM.

import Stencil in Svelte

I have a Monorepo with a svelte project and a Stencil component library. On the Stencil website they very clearly describe how to integrate the library with, for example, Angular
import { defineCustomElements } from 'test-components/loader';
defineCustomElements(window);
Super easy. But now I would like to use it too in a Svelte project ..... not so super easy anymore :(
When I try to do something similar as described above I get serious errors
fbp/dist is where the Stencil files are.
When I build my Stencil project first and copy my dist into the public folder and load ./dist/fbp.js in the head of index.html it all works. But it would be a lot easier if I could include it similar as it does with Angular. Any suggestions?
Update: Added emitCss which gives
Somewhere at the end it stats: Error: Unexpected token (Note that you need plugins to import files that are not JavaScript)
UPDATE: With the fixes of #Sambor, Svelte is now able to download the web component, which unfortunately fails

I have created a new project and I manage to reproduce the same problem.
At first, I was thinking is related to typescript and I've tried bunch of plugins in rollup like : #tscc/rollup-plugin-tscc, rollup-plugin-typescript but it didn't work.
I also tried rollup-plugin-amd with same results...
Then I've tried to change the main output format and use es instead of iife.
This way it also required to change the output to a directory instead of file (because of multiple file generation).
And surprisingly this way it seems to work.
here is my code:
/// index.html
<head>
<meta charset='utf-8'>
<meta name='viewport' content='width=device-width,initial-scale=1'>
<title>Test</title>
<link rel='stylesheet' href='build/bundle.css'>
<script type="module" defer src='build/main.js'></script>
</head>
<body>
</body>
</html>
Note: main.js is imported as module.
/// main.js
import App from './App.svelte';
import { applyPolyfills, defineCustomElements } from '../my-comp/loader';
applyPolyfills().then(() => {
defineCustomElements(window);
});
const app = new App({ target: document.body });
export default app;
/// rollup.config
import svelte from 'rollup-plugin-svelte';
import resolve from 'rollup-plugin-node-resolve';
import commonjs from 'rollup-plugin-commonjs';
import livereload from 'rollup-plugin-livereload';
import { terser } from 'rollup-plugin-terser';
import postcss from 'rollup-plugin-postcss';
import autoPreprocess from 'svelte-preprocess';
import json from '#rollup/plugin-json';
const production = !process.env.ROLLUP_WATCH;
export default {
input: 'src/main.js',
output: {
sourcemap: true,
format: 'es',
name: 'app',
dir: 'public/build'
},
plugins: [
json(),
svelte({
// Enables run-time checks when not in production.
dev: !production,
// Extracts any component CSS out into a separate file — better for performance.
css: css => css.write('public/build/bundle.css'),
// Emit CSS as "files" for other plugins to process
emitCss: true,
preprocess: autoPreprocess()
}),
resolve({
browser: true,
dedupe: importee => importee === 'svelte' || importee.startsWith('svelte/')
}),
commonjs(),
postcss({
extract: true,
minimize: true,
use: [
['sass', {
includePaths: ['./node_modules']
}]
]
}),
// In dev mode, call `npm run start` once the bundle has been generated
!production && serve(),
// Watches the `public` directory and refresh the browser on changes when not in production.
!production && livereload('public'),
// Minify for production.
production && terser()
],
watch: {
clearScreen: false
}
};
function serve() {
let started = false;
return {
writeBundle() {
if (!started) {
started = true;
require('child_process').spawn('npm', ['run', 'start', '--', '--dev'], {
stdio: ['ignore', 'inherit', 'inherit'],
shell: true
});
}
}
};
}
Note: I took my config from another svelte project (you can ignore uninteresting plugins)
Now it seems to be working fine, but I think is just the starting point :) because there are some known issues with stencil itself which I come across;
core-3d1820a5.js:97 TypeError: Failed to fetch dynamically imported module: http://localhost:57231/build/my-component.entry.js
core-3d1820a5.js:863 Uncaught (in promise) TypeError: Cannot read property 'isProxied' of undefined
https://github.com/sveltejs/sapper/issues/464
https://github.com/ionic-team/stencil/issues/1981
same with react: Unable to integrate stenciljs component in React application
This is not the completely working solution, but I thought it may help you for the next steps...

I’m still having the same issue in 2020. Surprisingly, the webpack template is working fine. Switching to that for now, until this is resolved.
https://github.com/sveltejs/template-webpack

i18next not loading files in backend

Hi I am using i18next in my Node JS Application.
The following is the config code for i18next:
const i18nextBackend = require('i18next-node-fs-backend');
i18n
.use(i18nextBackend)
.init({
fallbackLng: 'en',
debug: true,
backend: {
loadPath: 'locales/{{lng}}.json',
addPath: 'locales/{{lng}}.json',
jsonIndent: 2,
},
}, (err, t) => {
// init set content
console.log(t);
// console.log('INIT DONE');
});
console.log(i18n.t('hello'));
I have en.js in my locales folder in which JSON format data is there. But the file is unable to load. Can anybody tell how to give the path name in loadPath properly?

looks like you did not add a backend plugin at all. https://github.com/i18next/i18next-node-fs-backend filesystem backend might be what you search