jQuery：年月日三级联动

 1 <%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default3.aspx.cs" Inherits="Default3" %>
 2 
 3 <!DOCTYPE html>
 4 
 5 <html xmlns="http://www.w3.org/1999/xhtml">
 6 <head runat="server">
 7 <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
 8     <script src="js/jquery-1.7.2.min.js"></script>
 9     <title></title>
10 </head>
11 <body>
12     <form id="form1" runat="server">
13     <div>
14         <asp:DropDownList ID="dr_year" runat="server"></asp:DropDownList>年
15         <asp:DropDownList ID="dr_month" runat="server"></asp:DropDownList>月
16         <asp:DropDownList ID="dr_day" runat="server"></asp:DropDownList>日
17     </div>
18     </form>
19 </body>
20 </html>
21 <script>
22     var days = 0;
23     years();
24     months();
25     Days();
26     var date = new Date();
27     $("#dr_year").val(date.getFullYear());
28     $("#dr_month").val((date.getMonth() + 1));
29     $("#dr_day").val(date.getDate());
30     $("#dr_year").change(function () {
31         months();
32         Days();
33     });
34 
35     $("#dr_month").change(function () {
36         Days();
37     });
38     function years()
39     {
40         for(var i=1900;i<=2100;i++)
41         {
42             var str = "<option value="" + i + "">" + i+ "</option>";
43             $("#dr_year").append(str);
44         }
45     }
46     function months() {
47         $("#dr_month").empty();
48         for (var i = 1; i <= 12; i++) {
49             var str = "<option value="" + i + "">" + i + "</option>";
50             $("#dr_month").append(str);
51         }
52     }
53     function Days() {
54         $("#dr_day").empty();
55         if (parseInt($("#dr_month").val()) == 1 || parseInt($("#dr_month").val()) == 3 || parseInt($("#dr_month").val()) == 5 || parseInt($("#dr_month").val()) == 7 || parseInt($("#dr_month").val()) == 8 || parseInt($("#dr_month").val()) == 10 || parseInt($("#dr_month").val()) == 12) {
56             days = 31;
57         }
58         else if (parseInt($("#dr_month").val()) == 4 || parseInt($("#dr_month").val()) == 6 || parseInt($("#dr_month").val()) == 9 || parseInt($("#dr_month").val()) == 11) {
59             days = 30;
60         }
61         else {
62             if (parseInt($("#dr_year").val()) % 400 == 0 || (parseInt($("#dr_year").val()) % 4 == 0 && parseInt($("#dr_year").val()) % 100 != 0)) {
63                 days = 29;
64             }
65             else {
66                 days = 28;
67             }
68         }
69         for (var i = 1; i <= days; i++) {
70             var str = "<option value="" + i + "">" + i + "</option>";
71             $("#dr_day").append(str);
72         }
73     }
74 </script>

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原文地址：https://www.cnblogs.com/zblc2016/p/6075164.html