JavaScript Exercises: Check if an element is present in the Singly Linked list

JavaScript Singly Linked List: Exercise-18 with Solution

Get the index of an element in a SLL

Write a JavaScript program to check if an element is present in the Singly Linked list.

Sample Solution:

JavaScript Code:

class Node {
    // Constructor function for creating a new node with given data
    constructor(data) {
        this.data = data; // Assign the given data to the node
        this.next = null; // Initialize the pointer to the next node as null
    }
}
class SinglyLinkedList {
    // Constructor function for creating a new singly linked list with optional Head node
    constructor(Head = null) {
        this.Head = Head; // Initialize the Head node of the list
    }
  
add(newNode){
    let node = this.Head; // Start from the Head node
    if(node==null){ // If the list is empty
        this.Head = newNode; // Set the new node as the Head
        return;
    }
    while (node.next) { // Traverse the list until reaching the last node
        node = node.next; // Move to the next node
    }
    node.next = newNode; // Set the next pointer of the last node to the new node
}
  
is_present(val) {
  let current = this.Head; // Start from the Head node
  while (current) { // Iterate through the list
    if (current.data === val) { // If the value is found
      return true; // Return true indicating presence of value
    }
    current = current.next; // Move to the next node
  }
  return false; // Return false indicating absence of value
}
 
 displayList(){
    let node = this.Head; // Start from the Head node
    var str = "" // Initialize an empty string to store the list elements
    while (node) { // Iterate through the list
        str += node.data + "->"; // Append the data of the current node to the string
        node = node.next; // Move to the next node
    }
    str += "NULL" // Append "NULL" to indicate the end of the list
    console.log(str); // Print the string representing the list
  }
}
let numList = new SinglyLinkedList(); // Create a new instance of the SinglyLinkedList class
numList.add(new Node(12)); // Add nodes to the list
numList.add(new Node(13));
numList.add(new Node(14));
numList.add(new Node(15));
numList.add(new Node(14));
numList.add(new Node(16));
console.log("Singly Linked list:"); // Print the original list
numList.displayList();
result = numList.is_present(12); // Check if value 12 is present in the list
console.log("Is 12 present in the said link list: "+result); // Log the result
result = numList.is_present(14); // Check if value 14 is present in the list
console.log("Is 14 present in the said link list: "+result); // Log the result
result = numList.is_present(17); // Check if value 17 is present in the list
console.log("Is 17 present in the said link list: "+result); // Log the result
result = numList.is_present(19); // Check if value 19 is present in the list
console.log("Is 19 present in the said link list: "+result); // Log the result

Output:

Singly Linked list:
12->13->14->15->14->16->NULL
Is 12 present in the said link list: true
Is 14 present in the said link list: true
Is 17 present in the said link list: false
Is 19 present in the said link list: false

Flowchart:

Live Demo:

See the Pen javascript-singly-linked-list-exercise-18 by w3resource (@w3resource) on CodePen.

For more Practice: Solve these Related Problems:

• Write a JavaScript function that traverses a singly linked list to determine if a given value is present, returning a boolean.
• Write a JavaScript function that uses recursion to check for the presence of an element in a singly linked list.
• Write a JavaScript function that converts a singly linked list into an array and uses the includes() method to check for an element.
• Write a JavaScript function that searches for an element in a singly linked list and returns its node if found, otherwise false.

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