So i started using mongodb aggregate framework few days ago so i implemented a $limit and a $skip method to my project like this :

let content = await dataSources.WarehouseItem.aggregate([
    { $match: {} },
    { $limit: 2 },
    {
      $group: {
        _id: "$productName",
        quantity: { $first: "$quantity" },
      },
    },
  ]);

But this code instead of it returning 2 documents it returns only 1 but when i put 3 it returns 2 and when i put 4 it returns 3 and so on , and the skip method is also isn't working as expected , there is 4 documents inside of this db but it doesn't return 3 when i do this :

let content = await dataSources.WarehouseItem.aggregate([
    { $match: {} },
    { $skip: 1 },
    {
      $group: {
        _id: "$productName",
        quantity: { $last: "$quantity" },
      },
    },
  ]);

it returns the whole 4 documents