Question

我有以下javascript代码，在下拉列表中显示当前日期，月份和年份。代码如下：

var monthtext=['January','February','March','April','May','June','July','August','September','October','November','December'];

function populatedropdown(dayfield, monthfield, yearfield) {
   var today=new Date()
   var dayfield=document.getElementById(dayfield)
   var monthfield=document.getElementById(monthfield)
   var yearfield=document.getElementById(yearfield)
   for (var i=0; i<31; i++) {
      dayfield.options[i]=new Option(i+1)
   }
   dayfield.options[today.getDate()]=new Option(today.getDate(), today.getDate(), true, true) //select today's day
   for (var m=0; m<12; m++) {
      monthfield.options[m]=new Option(monthtext[m], monthtext[m])
   }
   monthfield.options[today.getMonth()]=new Option(monthtext[today.getMonth()], monthtext[today.getMonth()], true, true) //select today's month
   var thisyear=today.getFullYear()
   for (var y = 0; y < 100; y++) {
       yearfield.options[y] = new Option(thisyear, thisyear)
       thisyear -= 1
   }
   yearfield.options[0]=new Option(today.getFullYear(), today.getFullYear(), true, true) //select today's year
}

<script type="text/javascript">
//populatedropdown(id_of_day_select, id_of_month_select, id_of_year_select)
window.onload=function(){
populatedropdown("daydropdown", "monthdropdown", "yeardropdown")
}
</script>



 <select id="daydropdown" name="D-DOB"></select>  
   <select id="monthdropdown" name="M-DOB"></select>
   <select id="yeardropdown" name="Y-DOB"></select>

我希望将“选择日期”，“选择月份”和“选择年份”显示为默认值，以代替当前值：

<option value="">Select Day</option>

小提琴：https://jsfiddle.net/u2m243qf/1/

修改

我自己解决：

我重新组织了我的代码并得出了一个更简单的解决方案。新小提琴： https://jsfiddle.net/u2m243qf/9/

Answer 1

如果我了解您的请求，您希望在选项中显示默认值？如果是这样，请执行：

<option value="x" selected="your-selected"> Select day </option>

您还可以在此处找到有关该主题的更深入讨论： How can I set the default value for an HTML <select> element?

......在JS中它是：

dayfield.value = "Select Day";

显示日，月和年代替当前日，月和年

1 个答案: