Narrow argument type to the specific event being listened to

packages/embeds/embed-core/playground.ts

@@ -1,7 +1,8 @@
 import type { GlobalCal } from "./src/embed";
 
 const Cal = window.Cal as GlobalCal;
-const callback = function (e) {
+// eslint-disable-next-line @typescript-eslint/no-explicit-any
+const callback = function (e: any) {
   const detail = e.detail;
   console.log("Event: ", e.type, detail);
 };
@@ -27,6 +28,7 @@ const only = searchParams.get("only");
 const colorScheme = searchParams.get("color-scheme");
 const prerender = searchParams.get("prerender");
 
+// @ts-expect-error We haven't defined ENABLE_FUTURE_ROUTES as it is a playground specific variable.
 window.ENABLE_FUTURE_ROUTES = searchParams.get("future-routes") === "true";
 
 if (colorScheme) {
@@ -470,8 +472,15 @@ if (only === "all" || only == "ns:monthView") {
     }
   );
   Cal.ns.monthView("on", {
-    action: "*",
-    callback,
+    action: "bookingSuccessfulV2",
+    callback: (e) => {
+      const data = e.detail.data;
+      console.log("bookingSuccessfulV2", {
+        endTime: data.endTime,
+        startTime: data.startTime,
+        title: data.title,
+      });
+    },
   });
 }
 

packages/embeds/embed-core/src/embed.ts

@@ -141,10 +141,20 @@ function withColorScheme(
   return queryObject;
 }
 
+type allPossibleCallbacksAndActions = {
+  [K in keyof EventDataMap]: {
+    action: K;
+    callback: (arg0: CustomEvent<EventData<K>>) => void;
+  };
+}[keyof EventDataMap];
+
 type SingleInstructionMap = {
-  // TODO: This makes api("on", {}) loose it's generic type. Find a way to fix it.
-  // e.g. api("on", { action: "__dimensionChanged", callback: (e) => { /* `e.detail.data` has all possible values for all events/actions */} });
-  [K in keyof CalApi]: CalApi[K] extends (...args: never[]) => void ? [K, ...Parameters<CalApi[K]>] : never;
+  on: ["on", allPossibleCallbacksAndActions];
+  off: ["off", allPossibleCallbacksAndActions];
+} & {
+  [K in Exclude<keyof CalApi, "on" | "off">]: CalApi[K] extends (...args: never[]) => void
+    ? [K, ...Parameters<CalApi[K]>]
+    : never;
 };
 
 type SingleInstruction = SingleInstructionMap[keyof SingleInstructionMap];

packages/embeds/embed-core/tsconfig.json

@@ -12,6 +12,6 @@
       "@calcom/embed-snippet": ["../embed-snippet/src"]
     }
   },
-  "include": ["src", "env.d.ts", "index.ts"],
+  "include": ["src", "env.d.ts", "index.ts", "playground.ts"],
   "exclude": ["dist", "build", "node_modules"]
 }