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：
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>动态改变菜单</title> <script type="text/javascript" src="jquery.js"></script> <script type="text/javascript" src="SelectMenu.js"></script> </head> <body> <form action="#"> <br/> <br/> <br/> <div class="Address"> <span class="Province">Province： <select> <option value="" selected="selected">Please Choose Province</option> <option value="HeBei">HeBei</option> <option value="ShanDong">ShanDong</option> </select> </span> <span class="City" style="display:none">City： <select> </select> </span> <span class="Area" style="display:none">Area： <select> </select> </span> <br/> <br/> <span class="AddressSelect" style="display:none"> </span> </div> </form> </body> </html> Javascript源码
$(document).ready(function () { //找到三个下拉框 var ProvinceSelect = $(".Province").children("select"); var CitySelect = $(".City").children("select"); var AreaSelect = $(".Area").children("select"); var AddressSelect=$(".AddressSelect"); //给第二个下拉框注册事件 ProvinceSelect.change(function () { //1、获取当前下拉框的值 var ProvinceValue = $(this).val(); //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 AreaSelect.parent().hide(); AddressSelect.hide(); AddressSelect.html(""); //2、如果值不为空，则显示城市下拉框 if (ProvinceValue != "") { CitySelect.html(""); $("<option value=''>Please Choose City</option>").appendTo(CitySelect); switch(ProvinceValue) { //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 //如果追求完美，这里还可以加一道缓存，防止重复获取 case "HeBei": var CityOfHeBei=["ShiJiaZhuang","CangZhou","LangFang"]; for(var i=0;i<CityOfHeBei.length;i++){ $("<option value='"+CityOfHeBei[i]+"'>"+CityOfHeBei[i]+"</option>").appendTo(CitySelect); } break; case "ShanDong": var CityOfShanDon=["JiNan","DeZhou","QingDao"]; for(var i=0;i<CityOfShanDon.length;i++){ $("<option value='"+CityOfShanDon[i]+"'>"+CityOfShanDon[i]+"</option>").appendTo(CitySelect); } break; } CitySelect.parent().show(); } else { CitySelect.parent().hide(); } }); //给第二个下拉框注册事件 CitySelect.change(function () { var CityValue = $(this).val(); AddressSelect.hide(); AreaSelect.parent().hide(); AddressSelect.html(""); if (CityValue != "") { AreaSelect.html(""); $("<option value=''>Please Choose Area</option>").appendTo(AreaSelect); switch(CityValue) { //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 //如果追求完美，这里还可以加一道缓存，防止重复获取 case "ShiJiaZhuang": var AreaOfCity=["GaoXinQu","KaiFaQu","XinHuaQu"]; for(var i=0;i<AreaOfCity.length;i++){ $("<option value='"+AreaOfCity[i]+"'>"+AreaOfCity[i]+"</option>").appendTo(AreaSelect); } break; case "CangZhou": var AreaOfCity=["XinHuaQu","YunHeQu"]; for(var i=0;i<AreaOfCity.length;i++){ $("<option value='"+AreaOfCity[i]+"'>"+AreaOfCity[i]+"</option>").appendTo(AreaSelect); } break; case "LangFang": var AreaOfCity=["AnCiQu","GuangYangQu"]; for(var i=0;i<AreaOfCity.length;i++){ $("<option value='"+AreaOfCity[i]+"'>"+AreaOfCity[i]+"</option>").appendTo(AreaSelect); } break; case "QingDao": var AreaOfCity=["GaoXinQu","KaiFaQu","XinHuaQu"]; for(var i=0;i<AreaOfCity.length;i++){ $("<option value='"+AreaOfCity[i]+"'>"+AreaOfCity[i]+"</option>").appendTo(AreaSelect); } break; case "DeZhou": var AreaOfCity=["XinHuaQu","YunHeQu"]; for(var i=0;i<AreaOfCity.length;i++){ $("<option value='"+AreaOfCity[i]+"'>"+AreaOfCity[i]+"</option>").appendTo(AreaSelect); } break; case "JiNan": var AreaOfCity=["AnCiQu","GuangYangQu"]; for(var i=0;i<AreaOfCity.length;i++){ $("<option value='"+AreaOfCity[i]+"'>"+AreaOfCity[i]+"</option>").appendTo(AreaSelect); } break; } AreaSelect.parent().show(); } else { AreaSelect.parent().hide(); } }); AreaSelect.change(function(){ var AreaValue=$(this).val(); AddressSelect.html(""); if (AreaValue!=""){ $("<span>The Address Is --Province: "+ProvinceSelect.val()+" City: "+CitySelect.val()+" Area: "+AreaSelect.val()+"</span>").appendTo(AddressSelect); AddressSelect.show(); //alert("The Address Is Province: "+ProvinceSelect.val()+" City: "+CitySelect.val()+" Area: "+AreaSelect.val()); } }) }); 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。