Add Queue typing

lib/util/Queue.js

@@ -1,23 +1,46 @@
 "use strict";
 
-module.exports = class Queue {
+/**
+ * @template T
+ */
+class Queue {
+	/**
+	 * @param {IterableIterator<T>=} items The initial elements.
+	 */
 	constructor(items) {
+		/** @private @type {Set<T>} */
 		this.set = new Set(items);
+		/** @private @type {Iterator<T>} */
 		this.iterator = this.set[Symbol.iterator]();
 	}
 
+	/**
+	 * Returns the number of elements in this queue.
+	 * @return {number} The number of elements in this queue.
+	 */
 	get length() {
 		return this.set.size;
 	}
 
+	/**
+	 * Appends the specified element to this queue.
+	 * @param {T} item The element to add.
+	 * @return {void}
+	 */
 	enqueue(item) {
 		this.set.add(item);
 	}
 
+	/**
+	 * Retrieves and removes the head of this queue.
+	 * @return {T | undefined} The head of the queue of `undefined` if this queue is empty.
+	 */
 	dequeue() {
 		const result = this.iterator.next();
 		if (result.done) return undefined;
 		this.set.delete(result.value);
 		return result.value;
 	}
-};
+}
+
+module.exports = Queue;