JavaScript Exercises: Check whether a Doubly Linked Lists is empty or not
JavaScript Data Structures: Exercise-3 with Solution
Write a JavaScript program to check whether a Doubly Linked Lists is empty or not. Return true otherwise false.
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++;
}
size() {
return this.length;
}
is_Empty(){
return this.length === 0;
};
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();
let linkedlist_empty = numList.is_Empty();
console.log("Check the said Doubly Linked lists is empty or not! "+linkedlist_empty);
new_numList = new DoublyLinkedList();
new_numList.printList();
linkedlist_empty = new_numList.is_Empty();
console.log("Check the said Doubly Linked lists is empty or not! "+linkedlist_empty);
Sample Output:
Original Doubly Linked Lists: 2 3 5 6 8 Check the said Doubly Linked lists is empty or not! false Check the said Doubly Linked lists is empty or not! true
Flowchart:

Live Demo:
See the Pen javascript-doubly-linked-list-exercise-3 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: Head and Tail of a Doubly Linked Lists.
What is the difficulty level of this exercise?
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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
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