我如何根据条件添加月份

Question

我希望根据下拉列表添加月份，但我已多次尝试对其进行编码。我仍然得到一个输出。我正在使用jQuery datepicker添加月份

$(function() {
	var p = document.getElementById("period");
	

    $(".firstcal").datepicker({
        dateFormat: "dd/mm/yy",
        onSelect: function(dateText, instance) {
            date = $.datepicker.parseDate(instance.settings.dateFormat, dateText, instance.settings);
			if(document.getElementById("onemonth").value == 1){
				date.setMonth(date.getMonth() +  1);
            $(".secondcal").datepicker("setDate", date);
			}else 
				if (document.getElementById("threemonth").value == 3){
				date.setMonth(date.getMonth() +  3);
            $(".secondcal").datepicker("setDate", date);
			}else if(document.getElementById("sixmonth").value ==6){
				date.setMonth(date.getMonth() +  6);
            $(".secondcal").datepicker("setDate", date);
			}
            
        }
    });
    $(".secondcal").datepicker({
        dateFormat: "dd/mm/yy"
    });
});

<label style="color: #f2f2f2">Pay Period</label> <br/>
<select id="period">
<option>Select the period</option>
<option  id="onemonth"value="1">one month</option>
 <option  id="threemonth"value="3">three month</option>
 <option  id="sixmonth"value="6">six month </option> <br/>
</select>
<br/><br/>
<label style="color: #f2f2f2" >Date (From,To)</label> <br/>
 <input type="text" class="firstcal"> <input type="text" class="secondcal">

Answer 1

您应该检查select标记的值而不是option标记。将脚本更改为以下内容，我将检查id为period的元素的值。

$(function() {
  var p = document.getElementById("period");


  $(".firstcal").datepicker({
    dateFormat: "dd/mm/yy",
    onSelect: function(dateText, instance) {
      date = $.datepicker.parseDate(instance.settings.dateFormat, dateText, instance.settings);
      if (document.getElementById("period").value == 1) {
        date.setMonth(date.getMonth() + 1);
        $(".secondcal").datepicker("setDate", date);
      } else
      if (document.getElementById("period").value == 3) {
        date.setMonth(date.getMonth() + 3);
        $(".secondcal").datepicker("setDate", date);
      } else if (document.getElementById("period").value == 6) {
        date.setMonth(date.getMonth() + 6);
        $(".secondcal").datepicker("setDate", date);
      }

    }
  });
  $(".secondcal").datepicker({
    dateFormat: "dd/mm/yy"
  });
});