Adds singly linked list demo.

example-project/src/demo_singly-linked-list.js

@@ -0,0 +1,108 @@
+// See https://codeburst.io/linked-lists-in-javascript-es6-code-part-1-6dd349c3dcc3
+/*
+After install the Debug Visualizer extension,
+press F1, enter "Open Debug Visualizer" and
+use the following code as expression to visualize.
+Then, press F5 and chose "node".
+```
+hedietDbgVis.createGraphFromPointers(
+	hedietDbgVis.tryEval([
+		"list.head",
+		"newNode",
+		"node",
+		"previous",
+		this.constructor.name === "LinkedList" ? "this.head" : "err",
+	]),
+	n => ({
+		id: n.data,
+		color: "lightblue",
+		label: `${n.data}`,
+		edges: [{ to: n.next, label: "next" }].filter(i => !!i.to),
+	})
+);
+```
+
+*/
+
+class LinkedList {
+	constructor() {
+		this.head = null;
+	}
+}
+
+class Node {
+	constructor(data, next = null) {
+		(this.data = data), (this.next = next);
+	}
+}
+
+LinkedList.prototype.insertAtBeginning = function(data) {
+	// A newNode object is created with property data
+	// and next = null
+	let newNode = new Node(data);
+	// The pointer next is assigned head pointer
+	// so that both pointers now point at the same node.
+	newNode.next = this.head;
+	// As we are inserting at the beginning the head pointer
+	// needs to now point at the newNode.
+	this.head = newNode;
+	return this.head;
+};
+
+LinkedList.prototype.getAt = function(index) {
+	let counter = 0;
+	let node = this.head;
+	while (node) {
+		if (counter === index) {
+			return node;
+		}
+		counter++;
+		node = node.next;
+	}
+	return null;
+};
+
+// The insertAt() function contains the steps to insert
+// a node at a given index.
+LinkedList.prototype.insertAt = function(data, index) {
+	// if the list is empty i.e. head = null
+	if (!this.head) {
+		this.head = new Node(data);
+		return;
+	}
+	// if new node needs to be inserted at the front
+	// of the list i.e. before the head.
+	if (index === 0) {
+		this.head = new Node(data, this.head);
+		return;
+	}
+	// else, use getAt() to find the previous node.
+	const previous = this.getAt(index - 1);
+	let newNode = new Node(data);
+	newNode.next = previous.next;
+	previous.next = newNode;
+
+	return this.head;
+};
+
+const list = new LinkedList();
+debugger; // Press F10 to continue
+list.insertAtBeginning("4");
+list.insertAtBeginning("3");
+list.insertAtBeginning("2");
+list.insertAtBeginning("1");
+
+list.insertAt("3.5", 3);
+
+console.log("finished");
+
+// Some Plotting.
+// Use `data` as expression to visualize.
+const data = [];
+for (let x = 0; x < 1000; x += 1) {
+	data.push(Math.sin(x / 10));
+
+	if (x % 10 === 0) {
+		console.log("step");
+	}
+}