feat: add Collection#sweep() (#2528)

src/client/Client.js

@@ -358,12 +358,9 @@ class Client extends BaseClient {
       if (!channel.messages) continue;
       channels++;
 
-      for (const message of channel.messages.values()) {
-        if (now - (message.editedTimestamp || message.createdTimestamp) > lifetimeMs) {
-          channel.messages.delete(message.id);
-          messages++;
-        }
-      }
+      messages += channel.messages.sweep(
+        message => now - (message.editedTimestamp || message.createdTimestamp) > lifetimeMs
+      );
     }
 
     this.emit(Events.DEBUG,

src/util/Collection.js

@@ -259,6 +259,21 @@ class Collection extends Map {
     return Boolean(this.find(propOrFn, value));
   }
 
+  /**
+   * Removes entries that satisfy the provided filter function.
+   * @param {Function} fn Function used to test (should return a boolean)
+   * @param {Object} [thisArg] Value to use as `this` when executing function
+   * @returns {number} The number of removed entries
+   */
+  sweep(fn, thisArg) {
+    if (thisArg) fn = fn.bind(thisArg);
+    const previousSize = this.size;
+    for (const [key, val] of this) {
+      if (fn(val, key, this)) this.delete(key);
+    }
+    return previousSize - this.size;
+  }
+
   /**
    * Identical to
    * [Array.filter()](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/filter),