我有两个组合框，第一个用于省，第二个用于城市/城镇。
我想在第一个组合框改变之后得到我的第二个组合框（城市/城镇）的值，并且在用户首先选择组合框后，第二个组合框将随ajax改变。
这是我的代码，但问题是警报会出现两次！
jQuery('#billing_state').on('change', function() {
jQuery('#billing_city').on('change', function() {
var state = jQuery(this).val();
alert(state);
});
});
答案 0 :(得分：2)
为什么要对事件进行重叠？只需在第一个组合上使用更改。
以下是一个例子：
state = {"1":["Rome","Milan","Parma"],"2":["Paris","Lile","Nice"],"3":["Algiers","Jijel","Bejaia"],"4":["London","Manchester"]}
$(document).ready(function(){
//this if you want that changing province this alert country value
$("#billing_state").on("change",function(e){
$("#billing_town").children().remove();
var city =state[$(this).val()];
if(!city) return;
$("#billing_town").append('<option value="">- Select -</option>')
for(i=0; i< city.length;i++) {
//console.log(city[i]);
$("#billing_town").append('<option value="'+city[i]+'">'+city[i]+'</option>');
}
});
// when changing country this alert country value itself
$("#billing_town").on("change",function(e){
alert($(this).val());
});
});<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
Province :
<select id="billing_state">
<option value="">- select -</option>
<option value="1">Italy</option>
<option value="2">France</option>
<option value="3">Algeria</option>
<option value="4">UK</option>
</select>
<br><br>
Country :
<select id="billing_town">
</select>
答案 1 :(得分：0)
这就是你想要的。试试下面的演示
<!DOCTYPE html>
<html>
<head>
<title></title>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js"></script>
</head>
<style type="text/css">
</style>
<body>
<label>Province</label>
<select id="province">
<option>california</option>
<option>austin</option>
<option>texas</option>
<option>colombo</option>
</select>
<hr>
<label>city</label>
<select id="city">
<option>colombo</option>
<option>canberra</option>
<option>silicon valley</option>
<option>ottawa</option>
</select>
</body>
<script type="text/javascript">
$("#province").on('change',function(){// in this line identify if there is any changes to first select box
var thevalue = $("#city").val(); // if there is any changes to first selection box, then at that time get the value of second selection box.
alert(thevalue); // to check the value of secod check box at the time chage put an alert.
});
</script>
</html>
或者如果您想根据用户选择的第一个选择框值显示值，您可以这样做。
<!DOCTYPE html>
<html>
<head>
<title></title>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js"></script>
</head>
<style type="text/css">
</style>
<body>
<label>Province</label>
<select id="province">
<option>california</option>
<option>austin</option>
<option>ottawa</option>
<option>western</option>
</select>
<hr>
<label>City</label>
<select id="city">
<option>--select--</option>
</select>
</body>
<script type="text/javascript">
$("#province").on('change',function(){// in this line identify if there is any changes to first select box
var thevalue = $(this).val(); // if there is any changes to first selection box, then at that time get the
$("#city").text("");
//display values according to the first value
if (thevalue == "california")
{
var cities = ["sillicon valley","st pauls","new york"];
for(var i=0;i<cities.length;i++)
{
var createoption = $('<option>'+cities[i]+'</option>');
$("#city").append(createoption);
}
}
else if(thevalue="austin")
{
var cities = ["mirage","manhatten","las vegas"];
for(var i=0;i<cities.length;i++)
{
var createoption = $('<option>'+cities[i]+'</option>');
$("#city").append(createoption);
}
}
else
{
//like above you can add relevent values.
}
});
</script>
</html>