adding 02 SharedWorker

pages/scripts/sharedworker.js

@@ -0,0 +1,36 @@
+const mutations = {
+  ADD: 'ADD',
+  SET: 'SET'
+};
+
+let browserInstances = [];
+let messages = [];
+
+onconnect = function(e) {
+  const port = e.ports[0];
+
+  browserInstances.push(port);
+
+  port.onmessage = function({ data }) {
+    switch(data.mutation) {
+      case mutations.ADD:
+        messages = [...messages, data.value];
+        break;
+      case mutations.SET:
+        messages = data.value;
+        break;
+    }
+
+    postMessage({ ...data, messages });
+  }
+}
+
+function postMessage(message) {
+  if (!Array.isArray(message.value)) {
+    message.value = [message.value];
+  }
+
+  browserInstances.map(instance => {
+    instance.postMessage(message);
+  });
+}