您好，谢谢您的时间。
我有一个带有ID付款和提交按钮的表单，但我的JavaScript中似乎有一个错误，因为我只收到警报消息但是如果我输入一个错误的名称，如一行哈希，页面仍会提交符号#######。下面的代码正是我的文件中的代码。
// form validation, makes sure that the user inputs the correct data types.
function validateinput(event){
var email = document.getElementById('email').value;
var firstname = document.getElementById('firstname').value;
var lastname = document.getElementById('lastname').value;
var message = document.getElementById('message').value;
var emailFilter = /^([a-zA-Z0-9_.-])+@(([a-zA-Z0-9-])+.)+([a-zA-Z0-9]{2,4})+$/;
var firstnameFilter = /^([" "a-zA-Z.-])+$/;
var lastnameFilter = /^([" "a-zA-Z.-])+$/;
var messageFilter = /^([" "a-zA-Z0-9_.-])+$/;
if (!emailFilter.test(email)) {
alert('!Enter a email. Or enter a valid email address.');
document.getElementById('payment').addEventListener('onsubmit', function(event) {event.preventDefault();});
return false;
}
if (!firstnameFilter.test(firstname)) {
alert('!Enter a first name. Or enter a valid name.');
document.getElementById('payment').addEventListener('onsubmit', function(event) {event.preventDefault();});
return false;
}
if (!lastnameFilter.test(lastname)) {
alert('!Enter a last name. Or enter a name., only letters');
document.getElementById('payment').addEventListener('onsubmit', function(event) {event.preventDefault();});
return false;
}
if (!messageFilter.test(message)) {
alert('!Enter a message.');
document.getElementById('payment').addEventListener('onsubmit', function(event) {event.preventDefault();});
return false;
}
alert ('Your order was submited')
}
document.getElementById('payment').addEventListener("submit", validateinput)
还试过其他方法，认为它们在这个页面上看起来不太合适但在其他方面有用吗？
就像在我的联系页面上使用的那个更改var名称和id一样，
function validateinput(event){
var address1 = document.getElementById('address1').value;
var postcode = document.getElementById('postcode').value;
var address1Filter = /^([" "a-zA-Z0-9_.-])+$/;
var postcodeFilter = /^([" "a-zA-Z0-9_.-])+$/;
var formValid = true;
if (!address1Filter.test(address1)) {
alert('!Enter an address. Or enter a valid address., only letters and numbers');
formValid = false;
event.preventDefault();
return false;
}
if (!postcodeFilter.test(postcode)) {
alert('!Enter a postcode. Or enter a valid postcode., only letters and numbers');
formValid = false;
event.preventDefault();
return false;
}
alert ('Your order was submited')
}
document.getElementById('payment').addEventListener("submit", validateinput)
那么我做错了什么？
html
<!doctype html>
<!-- name: Edwin martin -date: 30/11/2015 -task: a form with split up inputs using the
<fieldset> & <legend> tags -->
<html lang="en">
<head>
<title>contact</title>
<script type="text/javascript" src="scripts/contact2.js"> </script>
<!-- ensures the document is using the correct char set -->
<meta charset="utf-8">
<meta name="description" content="contact page">
<link rel="icon" href="images/fav.png" type="image/png"/>
<!--
The below section looks like a comment, but it's a conditional include statement.
It's ignored by all browsers except IE9. html5shiv is a library that fixes some HTML5
IE bugs.
-->
<!--[if lt IE 9]>
<script src="http://html5shiv.googlecode.com/svn/trunk/html5.js"></script>
<![endif]-->
<!-- pulls in the styles sheet -->
<link rel="stylesheet" href="styles/indexstyles.css">
</head>
<body onload="main()">
<!-- start of the form, id form sets the position, size, border style and color -->
<div id="form2">
<!-- sets the link position, list and text style of the header, id head color sets the background color for the division around the header -->
<div id="head">
<header id="headcolor">
<div id="toplinks">
<ul>
<li class="tl"> <input type="button" class="topbutton" name="b1" value="Index" onclick="location.href='index.html'"> </li>
<li class="tl"> <input type="button" class="topbutton" name="b1" value="order" onclick="location.href='order.html'"> </li>
</ul>
</div> <br>
<br>
</header>
<h1 id="title"> Contact </h1>
<p> southampton solent pizzas: southampton solent university branch. E Park Terrace, Southampton, Hampshire SO14 0YN </p>
</div>
<div id="map"> </div>
<!-- id payment sets the input boxs background color , position and border for invaild - vaild -->
<form id="payment">
<!-- Contact Information section -->
<fieldset>
<legend> Personal Information </legend>
<p> <label> First Name(*): </label> <input type="text" name="first_name" id="firstname" placeholder="enter a first name" class="add1"></p>
<p> <label> Last Name(*): </label> <input type="text" name="last_name" id="lastname" placeholder="enter a last name" class="add1"></p>
<p> <label> Email(*): </label> <input type="text" name="email" id="email" placeholder="enter a email" class="add1"></p>
<p> <label>Phone Number: </label> <input type="text" name="phone" id="phone"></p>
<p> <label> message(*): </label> <input type="text" name="message" id="message" placeholder="enter your message" class="add1"></p>
</fieldset>
<!-- Submit button -->
<input type="submit" class="submit_button">
<input type="reset" class="reset_button">
</form>
</div>
<script type="text/javascript" src="scripts/contact.js"> </script>
<script src="https://maps.googleapis.com/maps/api/js?callback=initMap" async defer></script>
</body>
</html>
我还有另一个JS脚本，您可以从两个不同的链接中看到。但即使我删除该链接 - 代码仍然提交错误输入，因为此代码只读取空输入
//onload callback function
function main() {
console.log("in main function");
var myForm = document.getElementById("payment");
myForm.addEventListener("submit",validateForm);
}
//validate callback function
function validateForm(event) {
var formValid = true;
var myForm = document.getElementById("payment");
if (myForm.first_name.value == "") {
formValid = false;
//display error message
document.getElementById("firstname").className += " formInvalid"; //add the class .formInvalid
//stop form from submitting
event.preventDefault();
}
if (myForm.last_name.value == "") {
formValid = false;
//display error message
document.getElementById("lastname").className += " formInvalid"; //add the class .formInvalid
//stop form from submitting
event.preventDefault();
}
if (myForm.email.value == "") {
formValid = false;
//display error message
document.getElementById("email").className += " formInvalid"; //add the class .formInvalid
//stop form from submitting
event.preventDefault();
}
if (myForm.message.value == "") {
formValid = false;
//display error message
document.getElementById("message").className += " formInvalid"; //add the class .formInvalid
//stop form from submitting
event.preventDefault();
}
}
答案 0 :(得分：0)
document.getElementById('payment').addEventListener("submit", validateinput)，问题是你要将参数传递给validateinput方法，但你不能这样做，将参数传递给回调方法引用，你应该包装它在这样的匿名函数中。
document.getElementById('payment').addEventListener("submit", function(event) {
validateinput(event);
});
答案 1 :(得分：0)
我认为你的Javascript过于复杂化了。如果您更改提交以直接调用该函数，则可以更轻松地处理否定状态。
for (int i = 0; i < list.size(); i++){
if(list.get(i) %2 == 0){
return list.get(i);
}
}
您需要稍微修改validateinput函数，因为您将不再传递事件。