This is a Deno module for queuing messages sent to a worker thread while top-level await is used in order to prevent missed messages.
In Javascript, a Web Worker module is expected to immediately synchronously
attach a message event listener to itself (through self.onmessage = ...
or
self.addEventListener("message", ...)
), or else messages sent to it before the
message event listener is attached will be lost. This is a problem when using
top-level await before attaching the message event listener because the worker
may receive messages before the top-level await is finished. This situation
easily arises when a worker module imports dependencies that use top-level await
internally.
This module solves issues like Worker's postMessage not working.
In a web worker, use the addMessageEventListener
function from this module
instead of self.onmessage = ...
to attach your message event listener and
process all queued events:
import { addMessageEventListener } from "https://deno.land/x/worker_message_queuer@v1.0.1/mod.ts";
import { exampleFunction } from "example/module-using-top-level-await";
addMessageEventListener((event) => {
console.log("Received message:", event.data);
});
As long as this module is statically imported in the worker module, it does not matter whether it is imported before or after other imports containing top-level await.