  selectElement.appendChild(option200);

        const option500 = document.createElement('option');
        option500.value = 500;
        option500.selected = true;        
        option500.appendChild(document.createTextNode("500ms"));
        selectElement.appendChild(option500);

        const option1000 = document.createElement('option');
        option1000.value = 1000
        option1000.appendChild(document.createTextNode("1000ms"));
        selectElement.appendChild(option1000);

        const opt