我在使我的JavaScript能够正确使用html时遇到问题。我需要“活动”下拉框与“城市”下拉框配合使用。例如，如果我选择“布里斯班”，然后单击活动框，则选项应为“城市游览，体育，骑自行车，博物馆，划船”，并且根据选择的城市而有所不同。
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<title>Reservations</title>
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" type="text/css" href="travel.css">
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.4.0/css/bootstrap.min.css">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.0/jquery.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.4.0/js/bootstrap.min.js"></script>
<link rel="icon" href="travel.png">
<style type="text/css">
body{
background-color: white;
}
</style>
</head>
<header>
<img class="imageheader" src="travel.PNG" alt="megatravel" align="left" width="145" height="145">
<div class="wrapper">
<nav role="navigation">
<h1><a href="travelindex.html">Mega Travel</a></h1>
<ul class="nav-ul">
<li><a href="travelindex.html">Home</a></li>
<li><a href="aboutus.html">About Us</a></li>
<li><a href="reservations.html">Reservations</a></li>
</ul>
<a href="aboutus.html"><a/>
<a href="travelindex.html"><a/>
</nav>
</div>
</header>
<body>
<div class="container">
<div class="col-4">
<h1><strong>Book a Reservation</strong></h1>
<form action="contactform.php" method="post" id="reservationform">
<div class="form-group">
<label for="name">Name</label>
<input type="text" id="name" class="form-control">
</div>
<div class="form-group">
<label for="email">Email</label>
<input type="text" id="email" class="form-control">
</div>
<div class="form-group">
<label for="phone">Phone Number</label>
<input type="text" name="phoneNum" id="phone" class="form-control">
</div>
<div class="form-group">
<label for="adults">Adults</label>
<input type="number" name="adultsNo" id="adults" class="form-control">
</div>
<div class="form-group">
<label for="children">Children</label>
<input type="number" name="children" id="children" class="form-control">
</div>
<div class="form-group">
<label for="city">City</label>
<select name="city" id="city" style="width: 250px" onchange="activitiesSelect()" class="form-control">
<option selected disabled>Select</option>
<option value="Brisbane">Brisbane</option>
<option value="Vancouver">Vancouver</option>
<option value="New_York_City">New York City</option>
<option value="Berlin">Berlin</option>
<option value="Cancun">Cancun</option>
</select>
</div>
<div class="form-group">
<label for="activity">Activity</label>
<select name="activity" id="activity" style="width: 250px" class="form-control">
<option selected disabled>Select</option>
</select>
</div>
<div class="form-group">
<label for="traveldate">Travel Date</label>
<input type="date" name="traveldate" id="traveldate" style="width: 250px" class="form-control">
</div>
<div class="form-group">
<button type="submit" form="reservationform" value="Submit" style="width: 100px">Submit</button>
</div>
</form>
</div>
</div>
<script src="megatravel.js"></script>
</body>
</html>
function myfunct() {
var docHeight = (document.height !== undefined) ? document.height : document.body.offsetHeight;
var cur_height=window.innerHeight;
var total_height=docHeight-cur_height;
alert(total_height/100);
//var amout=total_height/100;
}
{
var Brisbane = ["City Tours","Sports","Cycling","Museums","Boating"];
var Vancouver = ["Sailing","Beach","Hiking","Museums","Boating"];
var New_York_City = ["Museums", "Theatre", "Parks and Recreation", "City Tours"];
var Berlin = ["City Tours", "Museums", "Cycling"];
var Cancun = ["Parks and Recreation", "Beaches", "Boating", "Snorkeling"];
}
function activitiesSelect(){
var city=document.getElementById('city').value;
$('#activity').find('option').remove().end().append('<option value="none" disabled selected>Select</option>').val('none');
if(city=="Brisbane"){
for(i=0;i<Brisbane.length;i++){
var o = new Option(Brisbane[i], Brisbane[i]);
$(o).html(Brisbane[i]);
$("#activity").append(o);
}
}
else if(city=="Vancouver"){
for(i=0;i<Vancouver.length;i++){
var o = new Option(Vancouver[i], Vancouver[i]);
$(o).html(Vancouver[i]);
$("#activity").append(o);
}
}else if(city=="New_York_City"){
for(i=0;i<New_York_City.length;i++){
var o = new Option(New_York_City[i], New_York_City[i]);
$(o).html(New_York_City[i]);
$("#activity").append(o);
}
}else if(city=="Berlin"){
for(i=0;i<Berlin.length;i++){
var o = new Option(Berlin[i], Berlin[i]);
$(o).html(Berlin[i]);
$("#activity").append(o);
}
}else if(city=="Cancun"){
for(i=0;i<Cancun.length;i++){
var o = new Option(Cancun[i], Cancun[i]);
$(o).html(Cancun[i]);
$("#activity").append(o);
}
}
}
答案 0 :(得分：0)
考虑像这样更改JavaScript：
const cities = {
Brisbane: ["City Tours", "Sports", "Cycling", "Museums", "Boating"],
Vancouver: ["Sailing", "Beach", "Hiking", "Museums", "Boating"],
Berlin: ["City Tours", "Museums", "Cycling"],
Cancun: ["Parks and Recreation", "Beaches", "Boating", "Snorkeling"]
};
function activitiesSelect(e) {
const { value: city } = e.target;
const values = cities[city];
$("#activity")
.find("option")
.remove()
.end()
.append('<option value="none" disabled selected>Select</option>')
.val("none");
for (let i = 0; i < values.length; i++) {
var o = new Option(values[i], values[i]);
$(o).html(values[i]);
$("#activity").append(o);
}
}
document.getElementById("city").addEventListener("change", activitiesSelect);
然后从您的选择标记中删除onchange处理程序。
这使您的JavaScript和HTML分开，并且使用city对象避免了if ... else语句过多。