删除有序数组中的重复项

var removeDuplicates = function (nums) {
  let map = new Map();
  for (let index = 0; index < nums.length; index++) {
    const item = nums[index];
    if (map.has(item)) {
      nums.splice(index, 1);
      index--;
    } else {
      map.set(item, true);
    }
  }
  return nums.length;
};
console.log(removeDuplicates([1, 1, 2]));