Javascript实现动态菜单添加
在注册信息的时候，常常需要通过下拉菜单让用户选择，而且希望用户在第一个下拉框做的选择，影响第二个下拉框的内容。有时候，如果第一个下拉框不作出选择，第二个下拉框根本不会页面上显示，为了给用户呈现一个更清晰的页面。
先来看看效果：
Html源码：
[html]
1. <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
2. <html xmlns="http://www.w3.org/1999/xhtml">
3. <head>
4.
5. <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
6. <title>动态改变菜单</title>
7. <script type="text/javascript" src="jquery.js"></script>
8. <script type="text/javascript" src="SelectMenu.js"></script>
9.
10. </head>
11.
12. <body>
13. <form action="#">
14. <br/>
15. <br/>
16. <br/>
17.
18. <div class="Address">
19.
20. <span class="Province">Province：
21. <select>
22. <option value="" selected="selected">Please Choose Province</option>
23. <option value="HeBei">HeBei</option>
24. <option value="ShanDong">ShanDong</option>
25. </select>
26. </span>
27.
28. <span class="City" style="display:none">City：
29. <select>
30. </select>
31. </span>
32. <span class="Area" style="display:none">Area：
33. <select>
34. </select>
35. </span>
36. <br/>
37. <br/>
38. <span class="AddressSelect" style="display:none">
39. </span>
40. </div>
41.
42. </form>
43. </body>
44. </html>
Javascript源码
[javascript]
1. $(document).ready(function () {
2.
3. //找到三个下拉框
4. var ProvinceSelect = $(".Province").children("select");
5. var CitySelect = $(".City").children("select");
6. var AreaSelect = $(".Area").children("select");
7. var AddressSelect=$(".AddressSelect");
8.
9. //给第二个下拉框注册事件
10. ProvinceSelect.change(function () {
11.
12. //1、获取当前下拉框的值
13. var ProvinceValue = $(this).val();
14. //1.1只要第一个下拉框内容有变化，第三个下拉框就要隐藏起来
15. AreaSelect.parent().hide();
16. AddressSelect.hide();
17. AddressSelect.html("");
18. //2、如果值不为空，则显示城市下拉框
19. if (ProvinceValue != "") {
20. CitySelect.html("");
21. $("<option value=''>Please Choose City</option>").appendTo(CitySelect);
22. switch(ProvinceValue)
23. {
24. //实际项目中，这个城市数组肯定是在服务器获取的，这里为了简便，我就直接自定义了一个数组
25. //如果追求完美，这里还可以加一道缓存，防止重复获取
26. case "HeBei":
27. var CityOfHeBei=["ShiJiaZhuang","CangZhou","LangFang"];
28. for(var i=0;i<CityOfHeBei.length;i++){
29. $("<option value='"+CityOfHeBei[i]+"'>"+CityOfHeBei[i]+"</option>").appendTo(CitySelect);
30. }
31. break;
32. case "ShanDong":
33. var CityOfShanDon=["JiNan","DeZhou","QingDao"];
34. for(var i=0;i<CityOfShanDon.length;i++){
35. $("<option value='"+CityOfShanDon[i]+"'>"+CityOfShanDon[i]+"</option>").appendTo(CitySelect);
36. }
37. break;
38.
39. }
40. CitySelect.parent().show();
41. } else {
42. CitySelect.parent().hide();
43. }
44.
45. });
46.
47.
48.
49. //给第二个下拉框注册事件
50. CitySelect.change(function () {
51.
52. var CityValue = $(this).val();
53. AddressSelect.hide();
54. AreaSelect.parent().hide();
55. AddressSelect.html("");
56. if (CityValue != "") {
57. AreaSelect.html("");
58. $("<option value=''>Please Choose Area</option>").appendTo(AreaSelect);
59. switch(CityValue)
60. {
61. //实际项目中，这个区数组肯定是在服务器获取的，这里为了简便，我就直接自定义了一个数组
62. //如果追求完美，这里还可以加一道缓存，防止重复获取
63. case "ShiJiaZhuang":
64. var AreaOfCity=["GaoXinQu","KaiFaQu","XinHuaQu"];
65. for(var i=0;i<AreaOfCity.length;i++){
66. $("<option value='"+AreaOfCity[i]+"'>"+AreaOfCity[i]+"</option>").appendTo(AreaSelect);
67. }
68. break;
69. case "CangZhou":
70. var AreaOfCity=["XinHuaQu","YunHeQu"];
71. for(var i=0;i<AreaOfCity.length;i++){
72. $("<option value='"+AreaOfCity[i]+"'>"+AreaOfCity[i]+"</option>").appendTo(AreaSelect);
73. }
74. break;
75. case "LangFang":
76. var AreaOfCity=["AnCiQu","GuangYangQu"];
77. for(var i=0;i<AreaOfCity.length;i++){
78. $("<option value='"+AreaOfCity[i]+"'>"+AreaOfCity[i]+"</option>").appendTo(AreaSelect);
79. }
80. break;
81. case "QingDao":
82. var AreaOfCity=["GaoXinQu","KaiFaQu","XinHuaQu"];
83. for(var i=0;i<AreaOfCity.length;i++){
84. $("<option value='"+AreaOfCity[i]+"'>"+AreaOfCity[i]+"</option>").appendTo(AreaSelect);
85. }
86. break;
87. case "DeZhou":
88. var AreaOfCity=["XinHuaQu","YunHeQu"];
89. for(var i=0;i<AreaOfCity.length;i++){
90. $("<option value='"+AreaOfCity[i]+"'>"+AreaOfCity[i]+"</option>").appendTo(AreaSelect);
91. }
92. break;
93. case "JiNan":
94. var AreaOfCity=["AnCiQu","GuangYangQu"];
95. for(var i=0;i<AreaOfCity.length;i++){
96. $("<option value='"+AreaOfCity[i]+"'>"+AreaOfCity[i]+"</option>").appendTo(AreaSelect);
97. }
98. break;
99. }
100. AreaSelect.parent().show();
101.
102.
103. } else {
104. AreaSelect.parent().hide();
105. }
106.
107. });
108.
109. AreaSelect.change(function(){
110. var AreaValue=$(this).val();
111. AddressSelect.html("");
112. if (AreaValue!=""){
113. $("<span>The Address Is --Province: "+ProvinceSelect.val()+" City: "+CitySelect.val()+" Area: "+AreaSelect.val()+"</span>").appendTo(AddressSelect);
114. AddressSelect.show();
115. //alert("The Address Is Province: "+ProvinceSelect.val()+" City: "+CitySelect.val()+" Area: "+AreaSelect.val());
116. }
117. })
118.
119. });
这里还引用了Jquery，貌似实现这个效果，用不用都无所谓，最近为了熟悉Jquery的用法，所以就加上了。
摘自 贾琳的专栏
