add doubly list

Author: dmitrymorozoff

index.html

@@ -15,6 +15,7 @@
     <script src="./source/structures/stack.js" type="module"></script>
     <script src="./source/structures/queue.js" type="module"></script>
     <script src="./source/structures/singly-list.js" type="module"></script>
+    <script src="./source/structures/doubly-list.js" type="module"></script>
     <script src="./source/main.js" type="module"></script>
 </body>
 

source/structures/doubly-list.js

@@ -0,0 +1,127 @@
+class Node {
+    constructor(data) {
+        this.data = data;
+        this.next = null;
+        this.prev = null;
+    }
+}
+
+export default class DoublyList {
+    constructor(data) {
+        this.head = null;
+        this.size = 0;
+    }
+    addFirst(data) {
+        const newNode = new Node(data);
+        if (this.head === null && this.size < 1) {
+            this.head = newNode;
+        } else {
+            newNode.next = this.head;
+            this.head.prev = newNode;
+            this.head = newNode;
+        }
+        this.size++;
+    }
+    addLast(data) {
+        const newNode = new Node(data);
+        if (this.head === null && this.size < 1) {
+            this.head = newNode;
+        } else {
+            let current = this.head;
+            while (current.next.next !== null) {
+                current = current.next;
+            }
+            current.next.next = newNode;
+            newNode.prev = current.next;
+        }
+        this.size++;
+    }
+    insert(data, index) {
+        const newNode = new Node(data);
+        if (index < 0) {
+            return;
+        } else if (index === 0) {
+            this.addFirst(newNode.data);
+        } else if (index >= this.size) {
+            this.addLast(newNode.data);
+        } else {
+            let iterator = 0;
+            let current = this.head;
+            while (iterator !== index - 1) {
+                current = current.next;
+                iterator++;
+            }
+            newNode.next = current.next;
+            newNode.prev = current;
+            current.next.prev = newNode;
+            current.next = newNode;
+            this.size++;
+        }
+    }
+    searchNodeAt(index) {
+        if (index < 0 || index > this.size) {
+            return;
+        } else if (index === 0) {
+            return this.head;
+        } else {
+            let current = this.head;
+            let iterator = 0;
+            while (current.next !== null) {
+                if (iterator === index) {
+                    return current;
+                }
+                current = current.next;
+                iterator++;
+            }
+        }
+    }
+    remove(index) {
+        if (index < 0 || index >= this.size || this.size <= 0) {
+            return;
+        } else if (index === 0) {
+            this.size--;
+            if (this.size === 0) {
+                this.head = null;
+            } else {
+                const temp = this.head.next;
+                temp.prev = null;
+                this.head = temp;
+            }
+            return;
+        } else {
+            let current = this.head;
+            let iterator = 0;
+            while (iterator !== index - 1) {
+                current = current.next;
+                iterator++;
+            }
+            if (current.next.next === null) {
+                current.next = null;
+            } else {
+                current.next = current.next.next;
+                current.next.prev = current;
+            }
+        }
+        this.size--;
+    }
+    length() {
+        return this.size;
+    }
+    print() {
+        let iterator = this.head;
+        while (iterator !== null) {
+            console.log(iterator.data);
+            iterator = iterator.next;
+        }
+    }
+}
+
+let d = new DoublyList();
+d.addFirst(1);
+d.addFirst(2);
+d.addFirst(3);
+d.addFirst(4);
+d.addFirst(5);
+d.remove(4);
+d.print();
+console.log(d);