1 files changed, 32 insertions, 0 deletions
diff --git a/src/content/MessageListener.ts b/src/content/MessageListener.ts
new file mode 100644
index 0000000..105d028
--- /dev/null
+++ b/src/content/MessageListener.ts
@@ -0,0 +1,32 @@
+import { Message, valueOf } from '../shared/messages';
+
+export type WebMessageSender = Window | MessagePort | ServiceWorker | null;
+export type WebExtMessageSender = browser.runtime.MessageSender;
+
+export default class MessageListener {
+  onWebMessage(
+    listener: (msg: Message, sender: WebMessageSender) => void,
+  ) {
+    window.addEventListener('message', (event: MessageEvent) => {
+      let sender = event.source;
+      let message = null;
+      try {
+        message = JSON.parse(event.data);
+      } catch (e) {
+        // ignore unexpected message
+        return;
+      }
+      listener(message, sender);
+    });
+  }
+
+  onBackgroundMessage(
+    listener: (msg: Message, sender: WebExtMessageSender) => any,
+  ) {
+    browser.runtime.onMessage.addListener(
+      (msg: any, sender: WebExtMessageSender) => {
+        listener(valueOf(msg), sender);
+      },
+    );
+  }
+}