Unique Values Counter

Implement a function CountUniqueValues, which takes in a sorted Array of positive and negative integers.
It should count and return the number of unique values in the Array.

Thoughts:

• This is an easy question.
• It should be easily checked against using JavaScript.
• It should try to use pointers to track the position of values to be compared against.
• No need to mutate the original Array.

function CountUniqueValues(arr) {
    if (arr.length === 0) return 0;

    let uniqueValueIndex = 0;
    let counter = 1;

    for (let i = 1; i < arr.length; i++) {
        if (arr[i] !== arr[uniqueValueIndex]) {
            counter++;
            uniqueValueIndex = i;
        }
    }

    return counter;
}

// sample data
const sorted_array = [-10,-11,1,1,1,2,3,4,5,5,5,6,7,7,7,7,8];
// result
console.warn(CountUniqueValues(sorted_array));
// to be asserted against result
console.warn(Array.from(new Set(sorted_array)).length);