Implemented an event

extension/background.js

@@ -1,3 +1,6 @@
+browser.hello.onSomething.addListener(param1 => {
+  console.log(`Something happened: ${param1}`);
+});
 
 browser.hello.hello().then(
   message => console.log(`hello sez: "${message}"`)

extension/hello.js

@@ -1,12 +1,36 @@
+ChromeUtils.import("resource://gre/modules/ExtensionCommon.jsm");
+ChromeUtils.import("resource://gre/modules/ExtensionUtils.jsm");
+
+const { EventManager } = ExtensionCommon;
+const { EventEmitter } = ExtensionUtils;
+
+class HelloEventEmitter extends EventEmitter {
+  emitHelloEvent() {
+    console.log("Emitting hello-event from HelloEventEmitter");
+    this.emit("hello-event");
+  }
+}
 
 this.hello = class extends ExtensionAPI {
   getAPI(context) {
+    const helloEventEmitter = new HelloEventEmitter();
     return {
       hello: {
         async hello() {
+          helloEventEmitter.emitHelloEvent();
           return "Hello, world!";
         }
-      }
+      },
+      onSomething: new EventManager(context, "hello.onSomething", fire => {
+        const callback = value => {
+          console.log("Firing hello-event from hello experiments API");
+          fire.async(value);
+        };
+        helloEventEmitter.on("hello-event", callback);
+        return () => {
+          helloEventEmitter.off("hello-event", callback);
+        };
+      }).api()
     };
   }
 }

extension/schema.json

@@ -10,6 +10,19 @@
         "async": true,
         "parameters": []
       }
+    ],
+    "events": [
+      {
+        "name": "onSomething",
+        "description": "Description of the event",
+        "parameters": [
+          {
+            "name": "param1",
+            "description": "Description of the first callback parameter",
+            "type": "number"
+          }
+        ]
+      }
     ]
   }
 ]