merge two sorted Linked list

mergeLists.js

function mergeLists(head1, head2) {

    var result = new SinglyLinkedListNode();

    // case1
   if(head1==null){
       return head2;
   }else if(head2==null){
       return head1;
   }
    
    //case 2
    if(head1.data <= head2.data){

        result = head1;
        result.next = mergeLists(head1.next,head2)

    }else{
        result = head2;
        result.next = mergeLists(head1, head2.next)

    }

    return result;


}