Question

我有3个html <select>年，月和日。年和月都自动设置为当前年和当月。我纯粹是用PHP做的。然而，即使我已经做了

，由Javascript触发的那天似乎也不起作用

if (j == <?php echo date('d') ?>)  days_select.options[days_select.options.length] = new Option(j, j, true);

默认日期仍然是1而不是当天。甚至令人沮丧的是，当我在萤火虫上检查时，选定的日子是当天...我在编程中总是一个菜鸟，这就是为什么这些简单的东西对我来说很难掌握。请帮忙......

date_select.php

<body onload="loadDays();">
 <script type="text/javascript" >

  function loadDays() {
   var year = parseInt(document.getElementById('years').value);
   var month = document.getElementById('months').value;
   var months = new Array("January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December");
   var days = new Array(31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31);

   if ((year % 4) == 0)  days[1] = 29;

   var days_select = document.getElementById('days');
   days_select.options.length = 0;

   for(i in months) {
    if (month == months[i]) {

     for(var j = 1; j <= days[i]; j++ ) {
      if (j == <?php echo date('d') ?>)  days_select.options[days_select.options.length] = new Option(j, j, true);
      else days_select.options[days_select.options.length] = new Option(j, j);
     }
     break;
    }
   }
  }

 </script>

 <span style="display: table; ">
  <span style="display: table-cell; ">
   <select id="years" onchange="loadDays();">
    <?php 
     for($year = 1900; $year <= 2100; $year++ ) {
      if ($year == date('Y')) echo "<option value='$year' selected=''>" . $year . "</option>";
      else echo "<option value='$year'>" . $year . "</option>";
     }
    ?>
   </select>
  </span>
  &nbsp;
  <span style="display: table-cell; ">
   <select id="months" onchange="loadDays();">
    <?php 
     $months = array("January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December" );

     foreach($months as $month){
      if ($month == date('M')) echo "<option value='$month' selected=''> " . $month . "</option>";
      else echo "<option value='$month'> " . $month . "</option>";
     }
    ?>
   </select>
  </span>
  &nbsp;
  <span style="display: table-cell; ">
   <select id="days" >

   </select>
  </span>
 </span>
</body>

Answer 1

我认为可能是因为<?php echo date('d') ?>生成带有前导零的字符串"04"。您的j循环计数器是一个整数，并且永远不会匹配PHP输出的字符串。

尝试将其包装在Javascript的parseInt()函数中，或使用date('j')表示没有前导零。

if (j == parseInt(<?php echo date('d') ?>))

更好的是，只需使用Javascript自己的Date对象来获取当天。

var theDateObj = new Date();
var today = theDateObj.getDate(); // Will output int 4 for today.

Answer 2

我把它作为一个单独的答案，因为它是一个。

Option()的第三个参数是默认选择该选项，就好像它是在HTML中指定的那样。第四是现在是否真的被选中。在您的true电话中添加另一个Option()，这对我来说非常有用。

new Option(j, j, true, true)

html-select <option selected =“”>不起作用</option>

2 个答案: