remove-duplicates-from-sorted-list.js

/**
 * Definition for singly-linked list.
 * function ListNode(val) {
 *     this.val = val;
 *     this.next = null;
 * }
 */
/**
 * @param {ListNode} head
 * @return {ListNode}
 */
var deleteDuplicates = function(head) {
    if (!head || !head.next) return head
    
    var prev = head
    var current = prev.next
    
    while (current) {
        if (current.val === prev.val) {
            prev.next = current.next
            current = current.next
            continue
        }
        prev = current
        current = current.next
    }
    return head
};