$(document).ready(function () {
    //copy options
    let options = $('#villeDepart option').clone();
    //react on keyup in textbox
    $('#villeDepartText').keyup(function () {
        let val = $(this).val().toString().toLowerCase();
        $('#villeDepart').empty();
        //take only the options containing your filter text or all if empty
        options.filter(function (idx, el) {
            return val === '' || $(el).text().toLowerCase().indexOf(val) >= 0;
        }).appendTo('#villeDepart');//add it to list
    });

    //copy options
    let optionsArrive = $('#villeArrive option').clone();
    //react on keyup in textbox
    $('#villeArriveText').keyup(function () {
        let val = $(this).val().toString().toLowerCase();
        $('#villeArrive').empty();
        //take only the options containing your filter text or all if empty
        optionsArrive.filter(function (idx, el) {
            return val === '' || $(el).text().toLowerCase().indexOf(val) >= 0;
        }).appendTo('#villeArrive');//add it to list
    });
});