JavaScript Exercises: Size of a Singly Linked list

JavaScript Singly Linked List: Exercise-12 with Solution

Write a JavaScript program that calculates the size of a Singly Linked list.

Sample Solution:

JavaScript Code:

// Define a class representing a node in a singly linked list
class Node {
    constructor(data) {
        // Initialize the node with provided data
        this.data = data
        // Initialize the next pointer to null
        this.next = null                
    }
}

// Define a class representing a singly linked list
class SinglyLinkedList {
    constructor(Head = null) {
        // Initialize the head of the list
        this.Head = Head
    }

    // Method to add a new node to the end of the list
    add(newNode){
        // Start traversal from the head node
        let node = this.Head;
        // If the list is empty, set the new node as the head and return
        if(node == null){
            this.Head = newNode;
            return;
        }
        // Traverse the list until the last node
        while (node.next) {
            node = node.next;
        }
        // Set the next pointer of the last node to the new node
        node.next = newNode;
    }  

    // Method to get the size of the linked list
    size(){
        // Start traversal from the head node
        let current = this.Head;
        // Initialize a count variable to store the size of the list
        let count = 0;
        // Traverse the list and increment the count for each node
        while (current) {
            count++;
            current = current.next;
        }
        return count;
    }

    // Method to display the elements of the list
    displayList(){
        // Start traversal from the head node
        let node = this.Head;
        // Initialize an empty string to store the elements of the list
        var str = ""
        // Traverse the list and concatenate each element to the string
        while (node) {
            str += node.data + "->";
            node = node.next;
        }
        // Append "NULL" to indicate the end of the list
        str += "NULL"
        // Print the string containing the list elements
        console.log(str);  
    }
}

// Create an instance of the SinglyLinkedList class
let numList = new SinglyLinkedList();
// Add nodes with data values to the list
numList.add(new Node(12));
numList.add(new Node(13));
numList.add(new Node(14));
numList.add(new Node(15));
numList.add(new Node(14));
// Display the elements of the list
console.log("Singly Linked list:");
numList.displayList();
// Display the size of the list
console.log("Size of the said Singly Linked list:");
console.log(numList.size());
// Add more nodes to the list
console.log("Add more elements to the said linked list.");
numList.add(new Node(20));
numList.add(new Node(21));
numList.add(new Node(22));
// Display the updated elements of the list
numList.displayList();
// Display the updated size of the list
console.log("Updated size of the said Singly Linked list:");
console.log(numList.size());

Output:

Singly Linked list:
12->13->14->15->14->NULL
Size of the said list Singly Linked list:
5
Add more elements to the said linked list.
12->13->14->15->14->20->21->22->NULL
8

Flowchart:

Live Demo:

See the Pen javascript-singly-linked-list-exercise-12 by w3resource (@w3resource) on CodePen.

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