Implement stack push method

Author: KarenOk

Stack.js

@@ -0,0 +1,29 @@
+// Stack using a Singly Linked List
+
+class Node {
+	constructor(value) {
+		this.value = value;
+		this.next = null;
+	}
+}
+
+class Stack {
+	constructor(value) {
+		this.first = null;
+		this.last = null;
+		this.size = 0;
+	}
+
+	push(value) {
+		const node = new Node(value);
+		if (!this.size) this.first = this.last = node;
+		else {
+			node.next = this.first;
+			this.first = node;
+		}
+
+		this.size++;
+
+		return this.size;
+	}
+}