windows-user-space-emulator/page/public/emulator-worker.js

var logLines = [];
var lastFlush = new Date().getTime();

var msgQueue = [];

onmessage = async (event) => {
  const data = event.data;
  const payload = data.data;

  switch (data.message) {
    case "run":
      runEmulation(payload.file, payload.options, payload.persist);
      break;
    case "event":
      msgQueue.push(payload);
      break;
  }
};

function sendMessage(message, data) {
  postMessage({ message, data });
}

function flushLines() {
  const lines = logLines;
  logLines = [];
  lastFlush = new Date().getTime();
  sendMessage("log", lines);
}

function logLine(text) {
  logLines.push(text);

  const now = new Date().getTime();

  if (lastFlush + 15 < now) {
    flushLines();
  }
}

function notifyExit(code, persist) {
  flushLines();

  const finishExecution = () => {
    sendMessage("end", code);
    self.close();
  };

  if (persist) {
    FS.syncfs(false, finishExecution);
  } else {
    finishExecution();
  }
}

function handleMessage(message) {
  sendMessage("event", message);
}

function getMessageFromQueue() {
  if (msgQueue.length == 0) {
    return "";
  }

  return msgQueue.shift();
}

function runEmulation(file, options, persist) {
  const mainArguments = [...options, "-e", "./root", file];

  globalThis.Module = {
    arguments: mainArguments,
    noInitialRun: true,
    onRuntimeInitialized: function () {
      FS.mkdir("/root");
      FS.mount(IDBFS, {}, "/root");
      FS.syncfs(true, function (_) {
        Module.callMain(mainArguments);
      });
    },
    print: logLine,
    printErr: logLine,
    onAbort: () => notifyExit(null, persist),
    onExit: (code) => notifyExit(code, persist),
    postRun: flushLines,
  };

  importScripts("./analyzer.js");
}