@desmos/esbuild-worker-dedupe
v3.0.0
Published
Proof of concept for inlining web worker code with esbuild with shared dependencies deduplicated.
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Proof of concept for inlining web worker code with esbuild with shared dependencies deduplicated.
Try it
yarn
yarn example # check the JS console to see that the main thread and worker code executed successfully.
cat example/bundle.ts # notice that the code from shared.ts only appears once
How it works
The idea is to use a two-step process:
First, take advantage of code splitting to factor out the common dependencies between the main entrypoint and the worker, which produces three "chunks", that look sort of like:
main.js
import { SharedThing } from "./shared.js";
// src/main.ts
import { createWorker } from "inlined-worker!./worker"; // NOTE: we intentionally skipped this import in the first step.
// We'll come back to it in the next step.
console.log("main", new SharedThing().id);
createWorker();
worker.js
import { SharedThing } from "./shared.js";
// src/worker.ts
function doSomething() {
console.log("worker", new SharedThing().id);
}
doSomething();
shared.js
// src/shared.ts
var SharedThing = class {
constructor() {
this.id = Math.random();
}
};
export { SharedThing };
We don't write these chunks to disk -- our plugin configures ESBuild to generate them in memory.
Next, we manually combine these three chunks into a single one as follows:
- From
shared.js
, emit code that: a. wraps the original source in a function,__sharedModuleFn
. b. evaluates that function immediately to provide the actual exports fromshared.js
(e.g.SharedThing
in the example above), storing them as__sharedModuleExports
- From
worker.js
, emit code that creates a__workerFn
function that accepts an object holding the exports from the shared module, and then code that uses Function.toString() to assemble both of these, at runtime, into a string containing the full source of the worker. This string is used to create an object URL with which to instantiate the worker.