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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.

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.

How to include manual import() in Webpack Bundle

I am quite new to Webpack, so bear with me if thats a stupid question.
My goal is to transform my old, AMD based codebase to a ES6 Module based solution. What I am struggling with is handling dynamic import()s. So my app router works on a module basis, i.e. each route is mapped to a module path and then required. Since I know what modules will be included, I just add those dynamically imported modules to my r.js configuration and am able to build everything in a single file, with all require calls still working.
Now, I am trying to do the same with ES6 modules and Webpack. With my devmode this is no problem as I can just replace require() with import(). However I cannot get this to work with bundling. Either Webpack splits my code (and still fails to load the dynamic module anyways), or - if I use the Array format for the entry config, the dynamic module is included in the bundle but loading still fails: Error: Cannot find module '/src/app/DynClass.js'
This is how my Webpack config looks like:
const webpack = require('webpack');
const path = require('path');
module.exports = {
mode: "development",
entry: ['./main.js', './app/DynClass.js'],
output: {
filename: 'main.js',
path: path.resolve(__dirname, "../client/")
},
resolve: {
alias: {
"/src": path.resolve(__dirname, '')
}
},
module: {
rules: [
{
test: /\.tpl$/i,
use: 'raw-loader',
},
]
}
};
So basically I want to tell Webpack: "hey, there is another module (or more) that is to be loaded dynamically and I want it to be included in the bundle"
How can I do this?

So yeah, after much fiddling there seems to be a light at the end of the tunnel. Still, this is not a 100% solution and it is surely not for the faint of heart, as it is quite ugly and fragile. But still I want to share my approach with you:
1) manual parsing of my routes config
My router uses a config file looking like this:
import StaticClass from "/src/app/StaticClass.js";
export default {
StaticClass: {
match: /^\//,
module: StaticClass
},
DynClass: {
match: /^\//,
module: "/src/app/DynClass.js"
}
};
So as you can see the export is an object, with keys acting as the route id, and an object that contains the matches (regex based) and the module which should be executed by the router if the route matches. I can feed my router with both a Constructor function (or an object) for modules which are available immediatly (i.e. contained in the main chunk) or if the module value is a string, this means that the router has to load this module dynamically by using the path specified in the string.
So as I know what modules could be potentially loaded (but not if and when) I can now parse this file within my build process and transform the route config to something webpack can understand:
const path = require("path");
const fs = require("fs");
let routesSource = fs.readFileSync(path.resolve(__dirname, "app/routes.js"), "utf8");
routesSource = routesSource.substr(routesSource.indexOf("export default"));
routesSource = routesSource.replace(/module:\s*((?!".*").)*$/gm, "module: undefined,");
routesSource = routesSource.replace(/\r?\n|\r/g, "").replace("export default", "var routes = ");
eval(routesSource);
let dummySource = Object.entries(routes).reduce((acc, [routeName, routeConfig]) => {
if (typeof routeConfig.module === "string") {
return acc + `import(/* webpackChunkName: "${routeName}" */"${routeConfig.module}");`;
}
return acc;
}, "") + "export default ''";
(Yeah I know this is quite ugly and also a bit brittle so this surely could be done better)
Essentially I create a new, virtual module where every route entry which demands a dynamic import is translated, so:
DynClass: {
match: /^\//,
module: "/src/app/DynClass.js"
}
becomes:
import(/* webpackChunkName: "DynClass" */"/src/app/DynClass.js");
So the route id simply becomes the name of the chunk!
2) including the virtual module in the build
For this I use the virtual-module-webpack-plugin:
plugins: [
new VirtualModulePlugin({
moduleName: "./app/dummy.js",
contents: dummySource
})
],
Where dummySource is just a string containing the sourcecode of my virtual module I just have generated. Now, this module is pulled in and the "virtual imports" can be processed by webpack. But wait, I still need to import the dummy module, but I do not have any in my development mode (where I use everything natively, so no loaders).
So in my main code I do the following:
let isDev = false;
/** #remove */
isDev = true;
/** #endremove */
if (isDev) { import('./app/dummy.js'); }
Where "dummy.js" is just an empty stub module while I am in development mode. The parts between that special comments are removed while building (using the webpack-loader-clean-pragma loader), so while webpack "sees" the import for dummy.js, this code will not be executed in the build itself since then isDev evaluates to false. And since we already defined a virtual module with the same path, the virtual module is included while building just like I want, and of course all dependencies are resolved as well.
3) Handling the actual loading
For development, this is quite easy:
import routes from './app/routes.js';
Object.entries(routes).forEach(async ([routeId, route]) => {
if (typeof route.module === "function") {
new route.module;
} else {
const result = await import(route.module);
new result.default;
}
});
(Note that this is not the actual router code, just enough to help me with my PoC)
Well, but for the build I need something else, so I added some code specific to the build environment:
/** #remove */
const result = await import(route.module);
new result.default;
/** #endremove */
if (!isDev) {
if (typeof route.module === "string") { await __webpack_require__.e(routeId); }
const result = __webpack_require__(route.module.replace("/src", "."));
new result.default;
}
Now, the loading code for the dev environment is just stripped out, and there is another loading code that uses webpack internally. I also check if the module value is a function or string, and if it is the latter I invoke the internal require.ensure function to load the correct chunk: await __webpack_require__.e(routeId);. Remember that I named my chunks when generating the virtual module? Now thats why I still can find them now!
4) more needs to be done
Another thing I encountered is when several dynamically loaded modules have the same dependencies, webpack tries to generate more chunks with names like module1~module2.bundle.js, breaking my build. To counter this, I needed to make sure that all those shared modules go into a specific named bundle I called "shared":
optimization: {
splitChunks: {
chunks: "all",
name: "shared"
}
}
And when in production mode, I simply load this chunk manually before any dynamic modules depending on it are requested:
if (!isDev) {
await __webpack_require__.e("shared");
}
Again, this code only runs in production mode!
Finally, I have to prevent webpack renaming my modules (and chunks) to something like "1", "2" etc, but rather keep the names I just have defined:
optimization: {
namedChunks: true,
namedModules: true
}
Se yeah, there you have it! As I said this wasn't pretty but seems to work, at least with my simplified test setup. I really hope there aren't any blockers ahead of me when I do all the rest (like ESLint, SCSS etc)!

Error creating custom pages from local plugin within GatsbyJS

My goal is creating pages from local plugin. I wrote a custom plugin named my-custom-plugin. I've also installed gatsby-plugin-page-creator plugin to automatically create pages from my components outside default pages directory.
This is my project structure:
plugins
/my-custom-plugin
/gatsby-node.js
/package.json
src
/components
/pages
/single.js
gatsby-config.js
gatsby-node.js
...etc
gatsby-config.js (from root):
module.exports = {
plugins: [
`my-custom-plugin`,
{
resolve: `gatsby-plugin-page-creator`,
options: {
path: `${__dirname}/src/components/pages`,
}
},
]
}
plugins/my-custom-plugin/gatsby-node.js
const path = require('path')
const location = path.resolve(__dirname, '..', '..', '/src/components/pages')
exports.createPages = ({ actions }) => {
const { createPage } = actions
createPage({
path: `/sample-page`,
component: `${location}/single.js`,
context: {
slug: 'sample-page'
}
})
}
Unfortunately, I got error message The plugin "my-custom-plugin" created a page with a component that doesn't exist when running gatsby develop. Am I doing wrong? Any help?
Regards.

https://github.com/gatsbyjs/gatsby/tree/master/packages/gatsby-plugin-page-creator
You don't need a custom plugin. The README states that you only need to insert the config into gatsby-config.js.
Your current local plugin tries to do exactly that what the page-creator plugin already does.

How can I get PurifyCSSPlugin to remove my unused css in Angular6?

I'm trying to remove a lot of unused css within my sass files in my Angular 6 project.
I'm learned that there is a webpack plugin called PurifyCss.
Currently now, I'm unable to eject the webpack config in my angular project so I'm using ngw to help add the necessary plugins (to angular's webpack config) needed to extract the unused css in my sass files.
ngw.config.ts
import * as webpack from 'webpack';
import { Path } from '#angular-devkit/core';
import { NormalizedBrowserBuilderSchema } from '#angular-devkit/build-angular';
import * as PurifyCSSPlugin from 'purifycss-webpack';
import * as path from 'path';
import * as glob from 'glob';
export type WebpackOptions<T = NormalizedBrowserBuilderSchema> = {
root: Path,
projectRoot: Path,
options: T;
};
const command = process.argv[2].toLowerCase();
export default function (config: webpack.Configuration, options: WebpackOptions) {
if (command === 'test') {
console.log('Test configuration is running');
}
console.log('To modify webpack build, you can use ngw.config.ts');
console.log('check path:', glob.sync(path.join(__dirname, 'src/**/*.html')));
config.plugins.push(
new PurifyCSSPlugin({
// This was suggested to help it actually remove the css from: https://github.com/webpack-contrib/purifycss-webpack/issues/54
// Although there is an error of: Error: data['resolveExtensions'] should NOT have additional properties
resolveExtensions: ['.html', '.js'],
// This causes the build to run but does not remove the unused css
paths: glob.sync(path.join(__dirname, 'src/**/*.html'))
}),
);
return config;
}
Using the paths property alone doesn't work and it was suggested to add resolveExtensions from here.
Although this leads to the error below when doing a ngw prod build:
Error: data['resolveExtensions'] should NOT have additional properties
How can I configure the PurifyCSSPlugin to remove unused css within sass files in an Angular-6-cli environement?
Note: I don't have much experience with webpack, so I'm not sure if this config only works with css files instead of scss files. (If so please correct me).
Thanks