如何将所选项目从下拉列表传递给Javascript函数? [英] How to pass the selected items from dropdownlist to a Javascript function ?

问题描述

亲爱的，

我需要使用 OnClientClick 将选择的项目从 DropDownList 传递给Javascript函数，以在botton受到对方欢迎时对其进行验证.

这是我的代码，不适用于我，任何人都可以告诉我问题出在哪里:

Dears ,

I need to pass the selected item from a DropDownList to a Javascript function using OnClientClick to validate it when the botton is cliked on the cilent side.

here is my code that does not work with me , can any body tell me where is the issue:

<asp:Button ID="Save" runat="server" Text="Save" Width="173px"

                        onclick="_Run_Click" OnClientClick="return DateValidation('<%=yFrom.ClientID%>','<%=yTo.ClientID%>')"  />

<script type="text/javascript">
    function DateValidation(yFrom, yTo) {

        var startYear = document.getElementById(yFrom);
        var endYear = document.getElementById(yTo);
        if (startYear != '' && endYear != '')
         {
             if (endYear < startYear)

            {

                alert('Start date cannot be greater than end date');

                 return false;

             }

            else { return true; }

         }

     }

</script>

谢谢，

Thanks,

推荐答案

var startYear = document.getElementById(yFrom);

这只是给您控制对象.听起来您想比较两个日期值.

试试:

This gave you just the control object. Sounds like you want to compare the two date value.

Try:

function DateValidation(yFrom, yTo) {

       var startYear = document.getElementById(yFrom);
       var endYear = document.getElementById(yTo);
       if (startYear.value != '' && endYear.value != '')
        {
            if (endYear.value < startYear.value)
           {
               alert('Start date cannot be greater than end date');
                return false;
            }
           else { return true; }
        }
    }

更新:
为了进行日期比较，您需要将文本框字符串转换为日期.

此处:

UPDATE:
For date comparison, you need to convert the textbox strings into dates.

Here:

function DateValidation(yFrom, yTo) {

       var startYear = document.getElementById(yFrom);
       var endYear = document.getElementById(yTo);
       if (startYear.value != '' && endYear.value != '')
        {
            Date endDate = new Date(endYear.value);
            Date startDate = new Date(startYear.value);
            if (endDate < startDate)
           {
               alert('Start date cannot be greater than end date');
                return false;
            }
           else { return true; }
        }
    }

确保文本框具有有效的Javascript日期，否则您将收到错误消息.

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