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：

<!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。