feat: add support for using keyword on discord.js Client and WebSocketManager (#10063)

* feat: add support for `using` keyword on client

* fix: use async dispose

* feat: add support for web socket manager disposing

* fix: use interface for client

---------

Co-authored-by: kodiakhq[bot] <49736102+kodiakhq[bot]@users.noreply.github.com>

packages/discord.js/src/client/BaseClient.js

@@ -106,6 +106,10 @@ class BaseClient extends EventEmitter {
   toJSON(...props) {
     return flatten(this, ...props);
   }
+
+  async [Symbol.asyncDispose]() {
+    await this.destroy();
+  }
 }
 
 module.exports = BaseClient;

packages/discord.js/src/index.js

@@ -1,7 +1,10 @@
 'use strict';
 
+const { polyfillDispose } = require('@discordjs/util');
 const { __exportStar } = require('tslib');
 
+polyfillDispose();
+
 // "Root" classes (starting points)
 exports.BaseClient = require('./client/BaseClient');
 exports.Client = require('./client/Client');

packages/discord.js/typings/index.d.ts

@@ -517,7 +517,7 @@ export abstract class Base {
   public valueOf(): string;
 }
 
-export class BaseClient extends EventEmitter {
+export class BaseClient extends EventEmitter implements AsyncDisposable {
   public constructor(options?: ClientOptions | WebhookClientOptions);
   private decrementMaxListeners(): void;
   private incrementMaxListeners(): void;
@@ -526,6 +526,7 @@ export class BaseClient extends EventEmitter {
   public rest: REST;
   public destroy(): void;
   public toJSON(...props: Record<string, boolean | string>[]): unknown;
+  public [Symbol.asyncDispose](): Promise<void>;
 }
 
 export type GuildCacheMessage<Cached extends CacheType> = CacheTypeReducer<

packages/util/src/functions/index.ts

@@ -3,3 +3,4 @@ export * from './range.js';
 export * from './calculateShardId.js';
 export * from './runtime.js';
 export * from './userAgentAppendix.js';
+export * from './polyfillDispose.js';

packages/util/src/functions/polyfillDispose.ts

@@ -0,0 +1,14 @@
+/**
+ * Polyfill for `Symbol.dispose` and `Symbol.asyncDispose` which is used as a part of
+ * {@link https://github.com/tc39/proposal-explicit-resource-management}. Node versions below 18.x
+ * don't have these symbols by default, so we need to polyfill them.
+ */
+export function polyfillDispose() {
+	// Polyfill for `Symbol.dispose` and `Symbol.asyncDispose` if not available.
+	// Taken from https://www.typescriptlang.org/docs/handbook/release-notes/typescript-5-2.html#using-declarations-and-explicit-resource-management
+
+	// @ts-expect-error This is a polyfill, so it's fine to write
+	Symbol.dispose ??= Symbol('Symbol.dispose');
+	// @ts-expect-error Same as above
+	Symbol.asyncDispose ??= Symbol('Symbol.asyncDispose');
+}

packages/ws/src/ws/WebSocketManager.ts

@@ -1,5 +1,6 @@
 import type { REST } from '@discordjs/rest';
 import { range, type Awaitable } from '@discordjs/util';
+import { polyfillDispose } from '@discordjs/util';
 import { AsyncEventEmitter } from '@vladfrangu/async_event_emitter';
 import {
 	Routes,
@@ -17,6 +18,9 @@ import type { IIdentifyThrottler } from '../throttling/IIdentifyThrottler.js';
 import { DefaultWebSocketManagerOptions, type CompressionMethod, type Encoding } from '../utils/constants.js';
 import type { WebSocketShardDestroyOptions, WebSocketShardEvents } from './WebSocketShard.js';
 
+// We put this here because in index.ts WebSocketManager seems to be outputted before polyfillDispose() is called from tsup.
+polyfillDispose();
+
 /**
  * Represents a range of shard ids
  */
@@ -199,7 +203,7 @@ export interface ManagerShardEventsMap {
 	];
 }
 
-export class WebSocketManager extends AsyncEventEmitter<ManagerShardEventsMap> {
+export class WebSocketManager extends AsyncEventEmitter<ManagerShardEventsMap> implements AsyncDisposable {
 	/**
 	 * The options being used by this manager
 	 */
@@ -334,4 +338,8 @@ export class WebSocketManager extends AsyncEventEmitter<ManagerShardEventsMap> {
 	public fetchStatus() {
 		return this.strategy.fetchStatus();
 	}
+
+	public async [Symbol.asyncDispose]() {
+		await this.destroy();
+	}
 }

tsconfig.json

@@ -42,7 +42,7 @@
 
 		// Language and Environment
 		"experimentalDecorators": true,
-		"lib": ["ESNext"],
+		"lib": ["ESNext", "esnext.disposable"],
 		"target": "ESNext",
 		"useDefineForClassFields": true
 	},