Remove Duplicates from Sorted Array https://leetcode.com/problems/remove-duplicates-from-sorted-array/

remove-duplicates.js

/**
 * @param {number[]} nums
 * @return {number}
 */
var removeDuplicates = function(nums) {
    const length = nums.length;
    let i = 1;
    let startIndex = 0;
    let count = 0;
    while(i < nums.length && nums[i] != undefined) {
        if (nums[startIndex] === nums[i]) {
            count++;
        } else {
            if (count) {
                nums.splice(startIndex, count);
            }
            startIndex = startIndex+1;
            i = startIndex;
            count = 0;   
        }
        i++;
    }
    if (count) {
        nums.splice(startIndex, count);
    }
    return nums.length;
};