var changeByHandler = false;

function AssignEventHandler() {
    var selectElement = document.getElementById("lb_stationSelect");
    if (selectElement) {
        selectElement.onchange = CopyValue;
    }
    
    var textElement = document.getElementById("tb_stationNo");
    if (textElement) {
        textElement.onkeydown = ClearSelectValue;
    }
}


function CopyValue() {
    changeByHandler = true;
    var selectElement = document.getElementById("lb_stationSelect");
    var inputElement = document.getElementById("tb_stationNo");
    if (inputElement && selectElement) {
        var selectedIndex = selectElement.selectedIndex;
        if (selectedIndex > 0) inputElement.value = selectElement.options[selectedIndex].text;
    }
    changeByHandler = false;
}

function ClearSelectValue() {
    if (changeByHandler) return;
    var selectElement = document.getElementById("lb_stationSelect");
    if (selectElement) {
        selectElement.selectedIndex = -1;
    }
}