feat(ThreadChannel): add a helper for pin and unpin

packages/discord.js/src/errors/ErrorCodes.js

@@ -90,6 +90,8 @@
  * @property {'StageChannelResolve'} StageChannelResolve
  * @property {'GuildScheduledEventResolve'} GuildScheduledEventResolve
  * @property {'FetchOwnerId'} FetchOwnerId
+ * @property {'CannotPinThreadOutOfForumChannel'} CannotPinThreadOutOfForumChannel
+ * @property {'CannotUnpinThreadOutOfForumChannel'} CannotUnpinThreadOutOfForumChannel
 
  * @property {'InvalidType'} InvalidType
  * @property {'InvalidElement'} InvalidElement
@@ -236,6 +238,8 @@ const keys = [
   'StageChannelResolve',
   'GuildScheduledEventResolve',
   'FetchOwnerId',
+  'CannotPinThreadOutOfForumChannel',
+  'CannotUnpinThreadOutOfForumChannel',
 
   'InvalidType',
   'InvalidElement',

packages/discord.js/src/errors/Messages.js

@@ -95,6 +95,8 @@ const Messages = {
   [DjsErrorCodes.StageChannelResolve]: 'Could not resolve channel to a stage channel.',
   [DjsErrorCodes.GuildScheduledEventResolve]: 'Could not resolve the guild scheduled event.',
   [DjsErrorCodes.FetchOwnerId]: "Couldn't resolve the guild ownerId to fetch the member.",
+  [DjsErrorCodes.CannotPinThreadOutOfForumChannel]: 'Cannot pin a thread which is not in a ForumChannel.',
+  [DjsErrorCodes.CannotUnpinThreadOutOfForumChannel]: 'Cannot unpin a thread which is not in a ForumChannel.',
 
   [DjsErrorCodes.InvalidType]: (name, expected, an = false) => `Supplied ${name} is not a${an ? 'n' : ''} ${expected}.`,
   [DjsErrorCodes.InvalidElement]: (type, name, elem) => `Supplied ${type} ${name} includes an invalid element: ${elem}`,

packages/discord.js/src/structures/ThreadChannel.js

@@ -1,6 +1,6 @@
 'use strict';
 
-const { ChannelType, PermissionFlagsBits, Routes } = require('discord-api-types/v10');
+const { ChannelType, PermissionFlagsBits, Routes, ChannelFlags } = require('discord-api-types/v10');
 const { BaseChannel } = require('./BaseChannel');
 const TextBasedChannel = require('./interfaces/TextBasedChannel');
 const { DiscordjsRangeError, ErrorCodes } = require('../errors');
@@ -456,6 +456,27 @@ class ThreadChannel extends BaseChannel {
   setAppliedTags(appliedTags, reason) {
     return this.edit({ appliedTags, reason });
   }
+
+  /**
+   * Pins this thread channel from the forum channel.
+   * @param {string} [reason] Reason for pinning
+   * @returns {Promise<ThreadChannel>}
+   */
+   pin(reason) {
+    if (this.parent.type !== ChannelType.ForumChannel) throw new DiscordjsError(ErrorCodes.CannotPinThreadOutOfForumChannel);
+    return this.edit({ flags: [ChannelFlags.Pinned], reason });
+  }
+
+  /**
+   * Unpins this thread channel from the forum channel.
+   * @param {string} [reason] Reason for unpinning
+   * @returns {Promise<ThreadChannel>}
+   */
+   unpin(reason) {
+    if (this.parent.type !== ChannelType.ForumChannel) throw new DiscordjsError(ErrorCodes.CannotUnpinThreadOutOfForumChannel);
+    const flags = [this.flags.remove(ChannelFlags.Pinned)];
+    return this.edit({ flags, reason });
+  }
 
   /**
    * Whether the client user is a member of the thread.

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

@@ -2640,6 +2640,8 @@ export class ThreadChannel<Forum extends boolean = boolean> extends TextBasedCha
   public setLocked(locked?: boolean, reason?: string): Promise<AnyThreadChannel>;
   public setName(name: string, reason?: string): Promise<AnyThreadChannel>;
   public setAppliedTags(appliedTags: Snowflake[], reason?: string): Promise<ThreadChannel<true>>;
+  public pin(reason?: string): Promise<ThreadChannel<true>>;
+  public unpin(reason?: string): Promise<ThreadChannel<true>>;
   public toString(): ChannelMention;
 }