Deno webworker example

coordinator.ts

import { serve } from "https://deno.land/std@0.140.0/http/server.ts";

serve(async (request) => {
  const worker = new Worker(new URL("./worker.ts", import.meta.url).href, {
    type: "module",
    name: "worker-" + (100 * Math.random()).toFixed(),
  });

  const data = await request.json();

  console.log("new task", data);
  worker.postMessage({ task: data });

  // Wait for a response from the worker to be fulfilled
  // Fulfill the promise when the mesage is passed.
  const result = new Promise((resolve, reject) => {
    worker.onmessage = (msg) => {
      resolve(msg.data);
    };
    worker.onerror = (err) => {
        err.preventDefault();
      reject(err.message);
    };
  });

  return result.then((output) => Response.json({ result: output }))
    .catch((reason) => {
      console.log("Caught reason");
      return Response.json({
        reason,
      }, {
        status: 400,
      });
    })
    .finally(() => worker.terminate());
}, {
  port: 9090,
});

console.log("server started @ 0.0.0.0:9090");

types.ts

/**
 * This worker can do one of two things: simple calculator or print things to console.
 */
export type WorkerParams =
  | CalculatorParams
  | PrinterParams;

export type Operation =
  | "add"
  | "subtract";

export interface CalculatorParams {
  type: "calculator";
  x: number;
  y: number;
  op: Operation;
}

export interface PrinterParams {
  type: "printer";
  text: string;
}

worker.ts

/**
 * Do worker things
 */
import { CalculatorParams, PrinterParams, WorkerParams } from "./types.ts";

// Install the app ID in the current environment.
const APP_ID = Deno.env.get("APP_ID")!;

console.log("worker starting");
self.onmessage = async (evt) => {
  const { task }: { task: WorkerParams } = evt.data;
  console.log("worker received task", task);

  switch (task.type) {
    case "calculator":
      self.postMessage(handleCalculator(task));
      return;
    case "printer":
      self.postMessage(handlePrinter(task));
      return;
    default:
      throw new Error("Invalid task type!");
  }
};

function handleCalculator(calculator: CalculatorParams) {
  switch (calculator.op) {
    case "add":
      return { result: calculator.x + calculator.y };
    case "subtract":
      return { result: calculator.x - calculator.y };
  }
}

function handlePrinter(printer: PrinterParams) {
  return printer.text;
}