JavaScript Exercises: Remove a node at the specified index in a singly linked list

JavaScript Singly Linked List: Exercise-11 with Solution

Write a JavaScript program that removes the node from the singly linked list at the specified index.

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 remove a node at a specified index position
    removeAt(index_pos){
        // Initialize a reference to the head node
        let nodes = this.Head;
        // If the index position is 0, remove the head node
        if(index_pos === 0) {
            // Check if the head node exists
            if(nodes !== null)
            {
                // Move the head pointer to the next node
                nodes = nodes.next;
                this.Head = nodes;
            }
            else
                throw Error("Index Out of Bound");
            return;
        }
        // Traverse the list until the node before the node to be removed
        while(--index_pos){
            // Check if the next node exists
            if(nodes.next !== null)
                nodes = nodes.next;
            else
                throw Error("Index Out of Bound");
        }
        // Remove the node by skipping it in the list
        nodes.next = nodes.next.next;
    }  

    // 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("Original Linked list:");
numList.displayList();
// Remove a node at index position 0
console.log("Remove the node where index position is 0:");
numList.removeAt(0);
numList.displayList();
// Remove a node at index position 3
console.log("Remove the node where index position is 3:");
numList.removeAt(3);
numList.displayList();
// Remove a node at index position 2
console.log("Remove the node where index position is 2:");
numList.removeAt(2);
numList.displayList();

Output:

12->13->14->15->14->NULL
Remove the node where index position is 0:
13->14->15->14->NULL
Remove the node where index position is 3:
13->14->15->NULL
Remove the node where index position is 2:
13->14->NULL

Flowchart:

Live Demo:

See the Pen javascript-singly-linked-list-exercise-11 by w3resource (@w3resource) on CodePen.

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