Using the solution below, I am able to get the solution correctly logged, however, it seems that Leetcode gets a different solution than my answer.

/**
  * @param {number[]} arr
  * @return {void} Do not return anything, modify arr in-place instead.
  */
var duplicateZeros = function(arr) {
  let finalLength = arr.length;
  for (let i = 0; i < finalLength; i++) {
    if(arr[i] == 0) {
        arr.splice(i, 0, 0);
        i++;
    }
  }
  arr = arr.slice(0, finalLength);
  console.log(arr);
};