Rename articles prefixed with js-

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

@@ -0,0 +1,74 @@
+---
+title: JavaScript Data Structures - Stack
+shortTitle: Stack
+type: story
+language: javascript
+tags: [class]
+author: chalarangelo
+cover: purple-flower-macro-1
+excerpt: A stack is a linear data structure which follows a last in, first out (LIFO) order of operations.
+dateModified: 2021-08-03T05:00:00-04:00
+---
+
+### Definition
+
+A stack is a linear data structure that behaves like a real-world stack of items. It follows a last in, first out (LIFO) order of operations, similar to its real-world counterpart. This means that new items are added to the top of the stack and items are removed from the top of the stack as well.
+
+![JavaScript Stack visualization](./illustrations/ds-stack.png)
+
+The main operations of a stack data structure are:
+
+- `push`: Adds an element to the top of the stack
+- `pop`: Removes an element from the top of the stack
+- `peek`: Retrieves the element at the top of the stack, without removing it
+- `isEmpty`: Checks if the stack is empty
+
+### Implementation
+
+```js
+class Stack {
+  constructor() {
+    this.items = [];
+  }
+
+  push(item) {
+    this.items.unshift(item);
+  }
+
+  pop(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 a `push()` method, which uses `Array.prototype.unshift()` to add an element to the start of the `items` array.
+- Define a `pop()` 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 stack = new Stack();
+
+stack.push('apples');
+stack.push('oranges');
+stack.push('pears');
+
+stack.isEmpty();    // false
+
+stack.peek();       // 'pears'
+
+stack.pop();        // 'pears'
+stack.pop();        // 'oranges'
+stack.pop();        // 'apples'
+
+stack.isEmpty();    // true
+```