JavaScript Exercises: Find the first index that matches a given element

JavaScript Singly Linked List: Exercise-8 with Solution

Write a JavaScript program to find the first index that matches a given element. Return -1 for no matching.

Sample Solution:

JavaScript Code:

class Node {
    constructor(data) {
        this.data = data
        this.next = null                
    }
}
class SinglyLinkedList {
    constructor(Head = null) {
        this.Head = Head
    }
add(newNode){
    let node = this.Head;
    if(node==null){
        this.Head = newNode;
        return;
    }
    while (node.next) {
        node = node.next;
    }
    node.next = newNode;
} 
indexOf(data){
    let ind = -1;
    let node = this.Head;
    while(node){
        ++ind;
        if(node.data === data) return ind;
        node = node.next;
    }
    return -1;
}  
 displayList(){
    let node = this.Head;
    var str = ""
    while (node) {
        str += node.data + "->";
        node = node.next;
    }
    str += "NULL"
    console.log(str);  
  }
}
let numList = new SinglyLinkedList();
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));
numList.displayList();
console.log("Find the first index that matches the value 14:")
console.log(numList.indexOf(14))
console.log("Find the first index that matches the value 5:")
console.log(numList.indexOf(5))

Sample Output:

12->13->14->15->14->NULL
Find the first index that matches the value 14:
2
Find the first index that matches the value 5:
-1

Flowchart:

Live Demo:

See the Pen javascript-singly-linked-list-exercise-8 by w3resource (@w3resource) on CodePen.

Improve this sample solution and post your code through Disqus

Singly Linked List Previous: Get a node in an existing singly linked list.
Singly Linked List Next: Check whether a single linked list is empty or not.