JavaScript Exercises: Head and Tail of a Doubly Linked Lists
JavaScript Data Structures: Exercise-4 with Solution
Write a JavaScript program to get the head and tail of a Doubly Linked Lists.
Sample Solution:
JavaScript Code:
class Node {
constructor(value) {
this.value = value;
this.next = null;
this.previous = null;
}
}
class DoublyLinkedList {
constructor(value) {
this.head = {
value: value,
next: null,
previous: null
};
this.length = 0;
this.tail = this.head;
}
// Insert node at end of the list
add(newNode) {
if (this.head === null) {
this.head = newNode;
this.tail = newNode;
}
else
{
newNode.previous = this.tail;
this.tail.next = newNode;
this.tail = newNode;
}
this.length++;
}
get_Head(){
return this.head;
}
get_Tail(){
return this.tail;
}
printList() {
let current = this.head;
let result = [];
while (current !== null) {
result.push(current.value);
current = current.next;
}
console.log(result.join(' '));
return this;
}
}
let numList = new DoublyLinkedList();
numList.add(new Node(2));
numList.add(new Node(3));
numList.add(new Node(5));
numList.add(new Node(6));
numList.add(new Node(8));
console.log("Original Doubly Linked Lists:")
numList.printList();
console.log("Head");
ghead = numList.get_Head();
console.log(ghead);
console.log("Tail");
ghead = numList.get_Tail();
console.log(ghead);
let new_numList = new DoublyLinkedList();
console.log("Original Doubly Linked Lists:")
new_numList.printList();
console.log("Head");
ghead = new_numList.get_Head();
console.log(ghead);
console.log("Tail");
ghead = new_numList.get_Tail();
console.log(ghead);
Sample Output:
"Original Doubly Linked Lists:" " 2 3 5 6 8" "Head" [object Object] { next: [object Object] { next: [object Object] { ... }, previous: [circular object Object], value: 2 }, previous: null, value: undefined } "Tail" [object Object] { next: null, previous: [object Object] { next: [circular object Object], previous: [object Object] { ... }, value: 6 }, value: 8 } "Original Doubly Linked Lists:" "" "Head" [object Object] { next: null, previous: null, value: undefined } "Tail" [object Object] { next: null, previous: null, value: undefined }
Flowchart:

Live Demo:
See the Pen javascript-doubly-linked-list-exercise-4 by w3resource (@w3resource) on CodePen.
Improve this sample solution and post your code through Disqus
Linked List Previous: Count number of nodes in a Doubly Linked Lists.
Linked List Next: Insert a new node at any position of a Doubly Linked List.
What is the difficulty level of this exercise?
Test your Programming skills with w3resource's quiz.
JavaScript: Tips of the Day
Shorten an array using its length property
A great way of shortening an array is by redefining its length property.
let array = [0, 1, 2, 3, 4, 5, 6, 6, 8, 9] array.length = 4 // Result: [0, 1, 2, 3]
Important to know though is that this is a destructive way of changing the array. This means you lose all the other values that used to be in the array.
Ref: https://bit.ly/2LBj213
- Weekly Trends
- Java Basic Programming Exercises
- SQL Subqueries
- Adventureworks Database Exercises
- C# Sharp Basic Exercises
- SQL COUNT() with distinct
- JavaScript String Exercises
- JavaScript HTML Form Validation
- Java Collection Exercises
- SQL COUNT() function
- SQL Inner Join
- JavaScript functions Exercises
- Python Tutorial
- Python Array Exercises
- SQL Cross Join
- C# Sharp Array Exercises