Use nanoevents instead of eventemitter3 (#9)

Reduces bundle size.

packages/app-connector/package.json

@@ -19,8 +19,7 @@
     "@parcnet-js/podspec": "workspace:*",
     "@pcd/gpc": "^0.0.8",
     "@pcd/pod": "^0.1.7",
-    "eventemitter3": "^5.0.1",
-    "json-bigint": "^1.0.0",
+    "nanoevents": "^9.0.0",
     "valibot": "^0.42.0"
   },
   "devDependencies": {

packages/app-connector/src/api_wrapper.ts

@@ -7,9 +7,13 @@ import type * as p from "@parcnet-js/podspec";
 import type { GPCBoundConfig, GPCProof, GPCRevealedClaims } from "@pcd/gpc";
 import type { PODEntries } from "@pcd/pod";
 import { POD } from "@pcd/pod";
-import { EventEmitter } from "eventemitter3";
+import { type Emitter, createNanoEvents } from "nanoevents";
 import type { ParcnetRPCConnector } from "./rpc_client.js";
 
+type SubscriptionEvents = {
+  update: (result: POD[]) => void;
+};
+
 /**
  * A Subscription object is returned to the caller when a subscription is
  * created. It allows the caller to attach event listeners to the subscription
@@ -19,13 +23,13 @@ import type { ParcnetRPCConnector } from "./rpc_client.js";
  * first creating the subscription, before any updates are available.
  */
 export class Subscription<E extends p.EntriesSchema> {
-  #emitter: EventEmitter;
+  #emitter: Emitter<SubscriptionEvents>;
   #query: p.PodSpec<E>;
   #api: ParcnetPODWrapper;
 
   constructor(
     query: p.PodSpec<E>,
-    emitter: EventEmitter,
+    emitter: Emitter<SubscriptionEvents>,
     api: ParcnetPODWrapper
   ) {
     this.#emitter = emitter;
@@ -37,18 +41,14 @@ export class Subscription<E extends p.EntriesSchema> {
     return this.#api.query(this.#query);
   }
 
-  on(event: "update", callback: (result: POD[]) => void): void {
-    this.#emitter.on(event, callback);
-  }
-
-  off(event: "update", callback: (result: POD[]) => void): void {
-    this.#emitter.off(event, callback);
+  on(event: "update", callback: (result: POD[]) => void): () => void {
+    return this.#emitter.on(event, callback);
   }
 }
 
 export class ParcnetPODWrapper {
   #api: ParcnetRPCConnector;
-  #subscriptionEmitters: Map<string, EventEmitter>;
+  #subscriptionEmitters: Map<string, Emitter<SubscriptionEvents>>;
 
   constructor(api: ParcnetRPCConnector) {
     this.#api = api;
@@ -73,7 +73,7 @@ export class ParcnetPODWrapper {
     query: p.PodSpec<E>
   ): Promise<Subscription<E>> {
     const subscriptionId = await this.#api.pod.subscribe(query.schema);
-    const emitter = new EventEmitter();
+    const emitter = createNanoEvents<SubscriptionEvents>();
     const subscription = new Subscription(query, emitter, this);
     this.#subscriptionEmitters.set(subscriptionId, emitter);
     return subscription;

packages/app-connector/src/rpc_client.ts

@@ -19,10 +19,14 @@ import {
 import type { PodspecProofRequest } from "@parcnet-js/podspec";
 import type { GPCBoundConfig, GPCProof, GPCRevealedClaims } from "@pcd/gpc";
 import type { PODEntries } from "@pcd/pod";
-import { EventEmitter } from "eventemitter3";
+import { type Emitter, createNanoEvents } from "nanoevents";
 import * as v from "valibot";
 import type { DialogController } from "./adapters/iframe.js";
 
+interface ParcnetEventSignatures {
+  "subscription-update": (result: SubscriptionUpdateResult) => void;
+}
+
 /**
  * The RPC connector handles low-level communication with the client.
  * It is responsible for sending and receiving messages via MessagePorts,
@@ -51,7 +55,7 @@ export class ParcnetRPCConnector implements ParcnetRPC, ParcnetEvents {
     number,
     { resolve: (value: unknown) => void; reject: (reason?: unknown) => void }
   >();
-  #emitter: EventEmitter;
+  #emitter: Emitter<ParcnetEventSignatures>;
   #connected = false;
 
   /**
@@ -108,7 +112,7 @@ export class ParcnetRPCConnector implements ParcnetRPC, ParcnetEvents {
   constructor(port: MessagePort, dialogController: DialogController) {
     this.#port = port;
     this.#dialogController = dialogController;
-    this.#emitter = new EventEmitter();
+    this.#emitter = createNanoEvents<ParcnetEventSignatures>();
     this.pod = {
       query: async (query: PODQuery): Promise<string[]> => {
         return this.#typedInvoke(
@@ -282,19 +286,8 @@ export class ParcnetRPCConnector implements ParcnetRPC, ParcnetEvents {
   on(
     event: "subscription-update",
     callback: (result: SubscriptionUpdateResult) => void
-  ): void {
-    this.#emitter.on("subscription-update", callback);
-  }
-
-  off(
-    event: "subscription-update",
-    callback: (result: SubscriptionUpdateResult) => void
-  ): void {
-    this.#emitter.off("subscription-update", callback);
-  }
-
-  removeAllListeners(): void {
-    this.#emitter.removeAllListeners("subscription-update");
+  ): () => void {
+    return this.#emitter.on("subscription-update", callback);
   }
 
   #emitSubscriptionUpdate(update: string[], subscriptionId: string): void {

packages/client-rpc/src/rpc_interfaces.ts

@@ -73,5 +73,5 @@ export interface ParcnetEvents {
   on: (
     event: "subscription-update",
     callback: (result: SubscriptionUpdateResult) => void
-  ) => void;
+  ) => () => void;
 }