2 pointers pattern: Count Unique values

countUniqueValues.js

function countUniqueValues(numbers){
  // add whatever parameters you deem necessary - good luck!
 if (!numbers.length) return 0;

 let left = 0;
 let right = 1;
 let counter = 1;

 while (right < numbers.length) {
     if (numbers[left] !== numbers[right]) {
         left = right;
         counter++;
     }
     right++;
 }
 return counter;
}