Table search on a filtered table?

Question

I have a search function that searches a table with 3 columns. I have now implemented a dropdown that filters the table based on a place but when using the search function, it searches the whole table not the items that are left from the dropdown. Below is my function to filter the table but is there anything I can add to filter based on what is being shown and not what the table has as a whole?

Using HTML + JS

    function filterTable(event) {
    var filter = event.target.value;
    var rows = document.querySelector("#rosterTable tbody").rows;

    for (var i = 0; i < rows.length; i++) {
        var firstCol = rows[i].cells[0].textContent;
        var fourthCol = rows[i].cells[3].textContent;
        var fifthCol = rows[i].cells[4].textContent;

        if (firstCol.indexOf(filter) > -1 || fourthCol.indexOf(filter) > -1 || fifthCol.indexOf(filter) > -1) {
            rows[i].style.display = "";
        } else {
            rows[i].style.display = "none";
        }
    }
}
document.querySelector('#myInput').addEventListener('keyup', filterTable, false);