Remove Duplicates from Sorted Array (different final results)

I am new at Programing and learning Javascript by doing some exercises from leetcode.com. I wanted to write a code to remove duplicates in a sorted array. When I use “console.log” at the end of the function to show the final result, I get the expected result. However when I use return (with the same variable) I get a wrong result. Can anybody please tell me, where I went wrong? Hier is my code:

/**
 * @param {number[]} nums
 * @return {number}
 */
var removeDuplicates = function (nums) {
  var newNums = []

  if (nums.length == 0) {
    newNums = []
  }

  for (var i = 0; i < nums.length; i++) {

    var curr = nums[i]
    var next = nums[i + 1]
    if (curr != next) {
      newNums.push(curr)
    }
  }

  console.log(newNums)
  return newNums
};

And here is a picture with the code and the results. the green arrow shows the output of (console.log), and the red one shows the output of (return). Thank you in advance! enter image description here

Answer

A slightly different approach by keeping the original object reference to the array and mutating the array by copying and adjusting the length of the array.

This approach does not need another array.

It basically checks if the predecessor is unequal to the actual item and copies the item to a new index j. This variable has the final length of the array and truncates the unwanted rest of the array.

function removeDuplicates(array) {
    let j = 0;
    for (let i = 0; i < array.length; i++) {
        if (array[i - 1] !== array[i]) array[j++] = array[i];
    }
    array.length = j;
    return array;
}

console.log(removeDuplicates([0, 1, 1, 2, 2, 2, 2, 3, 4, 5, 5]));