fix: type guard for sendable text-based channels (#10482)

* fix: type-guard for sendable text-based channels

* chore: suggested change

* Update packages/discord.js/typings/index.test-d.ts

Co-authored-by: Qjuh <76154676+Qjuh@users.noreply.github.com>

* fix: make isSendable strictly check for `.send`

* fix: tests

---------

Co-authored-by: Qjuh <76154676+Qjuh@users.noreply.github.com>
Co-authored-by: Jiralite <33201955+Jiralite@users.noreply.github.com>

packages/discord.js/src/structures/BaseChannel.js

@@ -155,6 +155,14 @@ class BaseChannel extends Base {
     return 'availableTags' in this;
   }
 
+  /**
+   * Indicates whether this channel is sendable.
+   * @returns {boolean}
+   */
+  isSendable() {
+    return 'send' in this;
+  }
+
   toJSON(...props) {
     return super.toJSON({ createdTimestamp: true }, ...props);
   }

packages/discord.js/src/util/Constants.js

@@ -117,9 +117,24 @@ exports.GuildTextBasedChannelTypes = [
  * * {@link ChannelType.PrivateThread}
  * * {@link ChannelType.GuildVoice}
  * * {@link ChannelType.GuildStageVoice}
+ * * {@link ChannelType.GroupDM}
  * @typedef {ChannelType[]} TextBasedChannelTypes
  */
-exports.TextBasedChannelTypes = [...exports.GuildTextBasedChannelTypes, ChannelType.DM];
+exports.TextBasedChannelTypes = [...exports.GuildTextBasedChannelTypes, ChannelType.DM, ChannelType.GroupDM];
+
+/**
+ * The types of channels that are text-based and can have messages sent into. The available types are:
+ * * {@link ChannelType.DM}
+ * * {@link ChannelType.GuildText}
+ * * {@link ChannelType.GuildAnnouncement}
+ * * {@link ChannelType.AnnouncementThread}
+ * * {@link ChannelType.PublicThread}
+ * * {@link ChannelType.PrivateThread}
+ * * {@link ChannelType.GuildVoice}
+ * * {@link ChannelType.GuildStageVoice}
+ * @typedef {ChannelType[]} SendableChannels
+ */
+exports.SendableChannels = [...exports.GuildTextBasedChannelTypes, ChannelType.DM];
 
 /**
  * The types of channels that are threads. The available types are:

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

@@ -975,6 +975,7 @@ export abstract class BaseChannel extends Base {
   public isDMBased(): this is PartialGroupDMChannel | DMChannel | PartialDMChannel;
   public isVoiceBased(): this is VoiceBasedChannel;
   public isThreadOnly(): this is ThreadOnlyChannel;
+  public isSendable(): this is SendableChannels;
   public toString(): ChannelMention | UserMention;
 }
 
@@ -3867,6 +3868,7 @@ export const Constants: {
   SweeperKeys: SweeperKey[];
   NonSystemMessageTypes: NonSystemMessageType[];
   TextBasedChannelTypes: TextBasedChannelTypes[];
+  SendableChannels: SendableChannelTypes[];
   GuildTextBasedChannelTypes: GuildTextBasedChannelTypes[];
   ThreadChannelTypes: ThreadChannelType[];
   VoiceBasedChannelTypes: VoiceBasedChannelTypes[];
@@ -6879,11 +6881,15 @@ export type Channel =
 
 export type TextBasedChannel = Exclude<Extract<Channel, { type: TextChannelType }>, ForumChannel | MediaChannel>;
 
+export type SendableChannels = Extract<Channel, { send: (...args: any[]) => any }>;
+
 export type TextBasedChannels = TextBasedChannel;
 
 export type TextBasedChannelTypes = TextBasedChannel['type'];
 
-export type GuildTextBasedChannelTypes = Exclude<TextBasedChannelTypes, ChannelType.DM>;
+export type GuildTextBasedChannelTypes = Exclude<TextBasedChannelTypes, ChannelType.DM | ChannelType.GroupDM>;
+
+export type SendableChannelTypes = SendableChannels['type'];
 
 export type VoiceBasedChannel = Extract<Channel, { bitrate: number }>;
 

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

@@ -209,6 +209,7 @@ import {
   ApplicationEmoji,
   ApplicationEmojiManager,
   StickerPack,
+  SendableChannels,
 } from '.';
 import { expectAssignable, expectDeprecated, expectNotAssignable, expectNotType, expectType } from 'tsd';
 import type { ContextMenuCommandBuilder, SlashCommandBuilder } from '@discordjs/builders';
@@ -2593,3 +2594,17 @@ declare const poll: Poll;
 expectType<Collection<Snowflake, StickerPack>>(await client.fetchStickerPacks());
 expectType<Collection<Snowflake, StickerPack>>(await client.fetchStickerPacks({}));
 expectType<StickerPack>(await client.fetchStickerPacks({ packId: snowflake }));
+
+client.on('interactionCreate', interaction => {
+  if (!interaction.channel) {
+    return;
+  }
+
+  // @ts-expect-error
+  interaction.channel.send();
+
+  if (interaction.channel.isSendable()) {
+    expectType<SendableChannels>(interaction.channel);
+    interaction.channel.send({ embeds: [] });
+  }
+});