Feature doubly linked list

src/doubly-linked-list/Node.ts

@@ -0,0 +1,13 @@
+type INodePointer = Node | null
+
+export class Node {
+  public prev: Node | null
+  public next: Node | null
+  public value: any
+
+  constructor(value: any, prev: Node | null = null, next: Node | null = null) {
+    this.value = value
+    this.prev = prev
+    this.next = next
+  }
+}

src/doubly-linked-list/__tests__/Node.ts

@@ -0,0 +1,48 @@
+import { Node } from '../Node'
+
+describe('Doubly linked list Node', () => {
+  it('should create an node with value', () => {
+    const node = new Node(1)
+    expect(node).toBeDefined()
+    expect(node).toBeInstanceOf(Node)
+    expect(node.value).toBe(1)
+    expect(node.next).toBe(null)
+    expect(node.prev).toBe(null)
+  })
+
+  it('should create node with any value', () => {
+    const objectValue = { value: 1, text: 'object' }
+    const arrayValue = [1, 2, 3, 4]
+    const functionValue = () => {
+      /** do nothing */
+    }
+
+    const valueList = [objectValue, arrayValue, functionValue]
+
+    valueList.forEach(value => {
+      const newNode = new Node(value)
+      expect(newNode.value).toEqual(value)
+    })
+  })
+
+  it('should link nodes togather', () => {
+    const first = new Node(1)
+    const second = new Node(2, first)
+    const three = new Node(3, second, first)
+
+    expect(first).toBeDefined()
+    expect(first.next).toBe(null)
+    expect(first.prev).toBe(null)
+    expect(first.value).toBe(1)
+
+    expect(second).toBeDefined()
+    expect(second.next).toBe(null)
+    expect(second.prev).toBe(first)
+    expect(second.value).toBe(2)
+
+    expect(three).toBeDefined()
+    expect(three.next).toBe(first)
+    expect(three.prev).toBe(second)
+    expect(three.value).toBe(3)
+  })
+})