copy worker code from old app

src/file.worker.js

@@ -1,3 +1,65 @@
 
-console.log('Hello Worker!');
+import { stringify } from 'javascript-stringify';
+import { MAX_DATA_SIZE } from './app.config';
 
+const log = console.log;
+console.log = (...a) => l(a);
+console.error = a => e(a);
+
+// limit chunk of data sent to browser, to avoid eventloop blocking
+const limitData = data => {
+  if (data.length > MAX_DATA_SIZE) {
+    return data.substr(0, MAX_DATA_SIZE);
+  }
+  return data;
+};
+
+const throttledPM = (() => {
+  const pm = postMessage;
+  self['postMessage'] = log;
+  const updateFreq = 50; // times per sec
+  const updateDelay = 1e3 / updateFreq;
+  let dataCache = [];
+  let lastUpdate = +new Date() - updateDelay;
+
+  return (data, finish = false, tryAgain = true) => {
+    const now = +new Date();
+    if (typeof data !== 'undefined') {
+      dataCache.push(data);
+    }
+
+    if (lastUpdate + updateDelay <= now || finish) {
+      pm(limitData(dataCache.join('\n')));
+      lastUpdate = now;
+      dataCache = [];
+    }
+
+    if (tryAgain) {
+      const nextTick = fn => setTimeout(fn, 0);
+      const tryAgainFn = _ => throttledPM([][0], false, false);
+      // try push data asap
+      setTimeout(tryAgainFn, 0);
+      // try push possibly cached data for async code
+      setTimeout(tryAgainFn, updateDelay);
+    }
+  };
+})();
+
+const l = args => {
+  const data = args.map(el => stringify(el, null, '  ')).join(', ');
+  throttledPM(data);
+};
+
+const e = err => {
+  const data = stringify(err);
+  throttledPM(data, true);
+};
+
+addEventListener('message', ({ data }) => {
+  try {
+    const code = new Function(data);
+    code();
+  } catch (e) {
+    console.error(e);
+  }
+});