Leetcode 92: Reverse Linked List II

Here is my leetcode solution in JavaScript:

/**
 * Definition for singly-linked list.
 * function ListNode(val, next) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.next = (next===undefined ? null : next)
 * }
 */
/**
 * @param {ListNode} head
 * @param {number} left
 * @param {number} right
 * @return {ListNode}
 */
 var  reverseBetween   = function (head , left , right ) {
     let  currPos   =   1 ;
     let  currNode   =  head ;
     let  startNode   =  head ;
     let  endNode   = null ;

     while (currPos   <  left ) {
        startNode   =  currNode ;
        currNode   =  currNode .next ;
        currPos  ++ ;
    }

     let  newList   = null ;
     let  tail   =  currNode ;

     while  (currPos   <=  right ) {
         const  next   =  currNode .next ;
        currNode .next   =  newList ;
        newList   =  currNode ;
        currNode   =  next ;
        currPos  ++ ;
    }

    startNode .next   =  newList ;
    tail .next   =  currNode ;

     if  (left   >   1 ) {
         return  head ;
    }

     return  newList ;


};

Link to problem.