Add TextBasedChannel#nsfw (excluding User and GuildMember) (#1419)

src/structures/GroupDMChannel.js

@@ -172,6 +172,7 @@ class GroupDMChannel extends Channel {
   awaitMessages() {}
   // Doesn't work on group DMs; bulkDelete() {}
   acknowledge() {}
+  get nsfw() {}
   _cacheMessage() {}
 }
 

src/structures/TextChannel.js

@@ -88,6 +88,7 @@ class TextChannel extends GuildChannel {
   stopTyping() {}
   get typing() {}
   get typingCount() {}
+  get nsfw() {}
   createCollector() {}
   createMessageCollector() {}
   awaitMessages() {}

src/structures/interfaces/TextBasedChannel.js

@@ -389,6 +389,15 @@ class TextBasedChannel {
     return this.client.rest.methods.ackTextChannel(this);
   }
 
+  /**
+   * If the Discord Client considers this channel NSFW
+   * @type {boolean}
+   * @readonly
+   */
+  get nsfw() {
+    return /^nsfw(-|$)/.test(this.name);
+  }
+
   _cacheMessage(message) {
     const maxSize = this.client.options.messageCacheMaxSize;
     if (maxSize === 0) return null;
@@ -493,7 +502,8 @@ exports.applyToClass = (structure, full = false, ignore = []) => {
       'fetchPinnedMessages',
       'createCollector',
       'createMessageCollector',
-      'awaitMessages'
+      'awaitMessages',
+      'nsfw'
     );
   }
   for (const prop of props) {