Rename articles prefixed with js-

snippets/js/s/data-structures-queue.md

@@ -0,0 +1,76 @@
+---
+title: JavaScript Data Structures - Queue
+shortTitle: Queue
+type: story
+language: javascript
+tags: [class]
+author: chalarangelo
+cover: purple-flower-macro-2
+excerpt: A queue is a linear data structure which follows a first in, first out (FIFO) order of operations.
+dateModified: 2021-07-29T05:00:00-04:00
+---
+
+### Definition
+
+A queue is a linear data structure that behaves like a real-world queue. It follows a first in, first out (FIFO) order of operations, similar to its real-world counterpart. This means that new items are added to the end of the queue, whereas items are removed from the start of the queue.
+
+![JavaScript Queue visualization](./illustrations/ds-queue.png)
+
+The main operations of a queue data structure are:
+
+- `enqueue`: Adds an element to the end of the queue
+- `dequeue`: Removes an element from the start of the queue
+- `peek`: Retrieves the element at the start of the queue, without removing it
+- `isEmpty`: Checks if the queue is empty
+
+### Implementation
+
+```js
+class Queue {
+  constructor() {
+    this.items = [];
+  }
+
+  enqueue(item) {
+    this.items.push(item);
+  }
+
+  dequeue(item) {
+    return this.items.shift();
+  }
+
+  peek(item) {
+    return this.items[0];
+  }
+
+  isEmpty() {
+    return this.items.length === 0;
+  }
+}
+```
+
+- Create a `class` with a `constructor` that initializes an empty array, `items`, for each instance.
+- Define an `enqueue()` method, which uses `Array.prototype.push()` to add an element to the end of the `items` array.
+- Define a `dequeue()` method, which uses `Array.prototype.shift()` to remove an element from the start of the `items` array.
+- Define a `peek()` method, which retrieves the value of the first element in the `items` array, without removing it.
+- Define an `isEmpty()` method, which uses `Array.prototype.length` to determine if the `items` array is empty.
+
+```js
+const queue = new Queue();
+
+queue.isEmpty();    // true
+
+queue.enqueue('A');
+queue.enqueue('B');
+queue.enqueue('C');
+queue.enqueue('D');
+queue.enqueue('E');
+
+queue.isEmpty();    // false
+
+queue.peek();       // 'A'
+
+queue.dequeue();    // 'A'
+queue.dequeue();    // 'B'
+queue.dequeue();    // 'C'
+```