LeetCode--Remove Linked List Elements

/**
 * Definition for singly-linked list.
 * function ListNode(val) {
 *     this.val = val;
 *     this.next = null;
 * }
 */
/**
 * @param {ListNode} head
 * @param {number} val
 * @return {ListNode}
 */
var removeElements = function(head, val) {
    var dummy = new ListNode(0);  
        dummy.next = head;  
        var p = dummy;  
        var q = head;  
        while(q !== null) {  
            if(q.val == val) {  
                p.next = q.next;  
            } else {  
                p = p.next;  
            }  
            q = q.next;  
        }  
          
        return dummy.next;  
};