如何操作 select 和 option

JS 碼如下：

var yesDateYear = "2023";
var yesDateMonth = "12";
var yesDateDay = "31";

var iDateYear = window.document.getElementById("iDateYear");
var iDateMonth = window.document.getElementById("iDateMonth");
var iDateDay = window.document.getElementById("iDateDay");

for (var i = 0; i < iDateYear.length; i++) {
    if (iDateYear.options[i].value == yesDateYear) {
        iDateYear.options[i].selected = true;
    }
}
for (var j = 0; j < iDateMonth.length; j++) {
    if (iDateMonth.options[j].value == yesDateMonth) {
        iDateMonth.options[j].selected = true;
    }
}
for (var k = 0; k < iDateDay.length; k++) {
    if (iDateDay.options[k].value == yesDateDay) {
        iDateDay.options[k].selected = true;
    }
}

HTML 碼如下：

<select name="dateYear" id="iDateYear"></select>
<select name="dateMonth" id="iDateMonth"></select>
<select name="dateDate" id="iDateDay"></select>