feat(betsy): add new emit async method

Author: christianalfoni

packages/node_modules/betsy/src/index.ts

@@ -24,6 +24,22 @@ export class EventEmitter<T> {
     }
   }
 
+  emitAsync<K extends keyof T>(event: K, msg: T[K]) {
+    const listeners = this.events.get(event) || []
+
+    setTimeout(() => {
+      for (let i = listeners.length - 1; i >= 0; i--) {
+        const listener = listeners[i]
+
+        listener.cb(msg)
+
+        if (listener.once) {
+          listeners.splice(i, 1)
+        }
+      }
+    })
+  }
+
   on<K extends keyof T>(event: K, cb: (msg: T[K]) => void) {
     this.addListener(event, cb, false)
   }