Insert node at beginning of linked list in node js

Write a program which is create and add new node at the beginning of linked list in node js.

Here given of code implementation process.

/*
    Node JS program for
    Insert node at beginning of linked list
*/
// Linked list node
class LinkNode
{
    constructor(data)
    {
        this.data = data;
        this.next = null;
    }
}
class SingleLL
{
    constructor()
    {
        this.head = null;
    }
    // Adding new node at beginning of linked list
    addNode(data)
    {
        // Create new node
        var node = new LinkNode(data);
        // Connect current node to previous head
        node.next = this.head;
        this.head = node;
    }
    // Display linked list element
    display()
    {
        if (this.head == null)
        {
            return;
        }
        var temp = this.head;
        // iterating linked list elements
        while (temp != null)
        {
            process.stdout.write( temp.data + " → ");
            // Visit to next node
            temp = temp.next;
        }
        process.stdout.write("NULL\n");
    }
}

function main()
{
    var sll = new SingleLL();
    // Linked list
    // 1 → 2 → 3 → 4 → 5 → 6 → 7 → 8 → NULL
    sll.addNode(8);
    sll.addNode(7);
    sll.addNode(6);
    sll.addNode(5);
    sll.addNode(4);
    sll.addNode(3);
    sll.addNode(2);
    sll.addNode(1);
    sll.display();
}
main();

 1 → 2 → 3 → 4 → 5 → 6 → 7 → 8 → NULL

Time complexity of above program is O(1).