我是JavaScript新手。我在一个html文件中有一个表单，它有一些文本字段。当有人点击提交按钮时，会调用一个JavaScript函数来完成一些工作(在本例中，是一个简单的警报)。它按我的意愿工作，当我填写文本字段并单击提交按钮时，它会调用JavaScript函数，该函数会显示警报。然而，问题是，当用户点击提交按钮，使某些字段为空和/或不遵循电子邮件地址的模式时，它会调用JavaScript函数(尽管HTML 5在表单中显示了警告)。我希望只有在没有HTML警告的情况下才调用JavaScript函数，我的意思是没有空字段，用户必须遵循电子邮件模式。谢谢你的帮助
HTML代码：
<form id="myForm" method="post" role="form" class="contactForm">
<input type="text" name="name" class="form-control" id="name" placeholder="Your Name" data-rule="minlen:4" data-msg="Please enter at least 4 chars" />
<input type="email" class="form-control" name="email" id="email" placeholder="Your Email" data-rule="email" data-msg="Please enter a valid email" />
<textarea class="form-control" name="message" id="message" rows="5" data-rule="required" data-msg="Please write something" placeholder="Message"></textarea>
<button id="submitFormData" onclick="SubmitFormData();" type="submit" class="button button-a button-big button-rouded">Send Message</button>
</form>
<script src="http://code.jquery.com/jquery-latest.js"></script>
<script src="alert.js"></script>
Javascript代码(alert.js)：
function SubmitFormData() {
var name = $("#name").val();
var email = $("#email").val();
var message = $("#message").val();
alert("SHOW SOMETHING HERE");
}
您可以在输入中使用必需的属性，还可以在提交表单中调用SubmitFormData()这是您修改后的代码：
function SubmitFormData() {
var name = $("#name").val();
var email = $("#email").val();
var message = $("#message").val();
alert("SHOW SOMETHING HERE");
}<form id="myForm" method="post" role="form" class="contactForm" onsubmit="SubmitFormData();">
<input type="text" name="name" class="form-control" id="name" placeholder="Your Name" data-rule="minlen:4" data-msg="Please enter at least 4 chars" required/>
<input type="email" class="form-control" name="email" id="email" placeholder="Your Email" data-rule="email" data-msg="Please enter a valid email" required/>
<textarea class="form-control" name="message" id="message" rows="5" data-rule="required" data-msg="Please write something" placeholder="Message" required></textarea>
<button id="submitFormData" type="submit" class="button button-a button-big button-rouded">Send Message</button>
</form>
<script src="http://code.jquery.com/jquery-latest.js"></script>您只需要将required属性添加到字段中，请参阅
以下是您想要通过使用表单验证JS插件。
<!DOCTYPE html>
<html>
<head>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
<script src="https://cdn.jsdelivr.net/jquery.validation/1.16.0/jquery.validate.min.js"></script>
<style>
form label {
display: inline-block;
width: 100px;
}
form div {
margin-bottom: 10px;
}
.error {
color: red;
margin-left: 5px;
}
label.error {
display: inline;
}
</style>
<script>
$(document).ready(function() {
$('form[id="second_form"]').validate({
rules: {
name: 'required',
user_email: {
required: true,
email: true,
},
message: {
required: true,
}
},
messages: {
name: 'This field is required',
user_email: 'Enter a valid email',
message: 'This field is required'
},
submitHandler: function(form) {
form.submit();
}
});
});
</script>
</head>
<body>
<h2>Example 2:</h2>
<form id="second_form" method="post" action="">
<div>
<label for="name">Name:</label>
<input type="text" name="name" class="form-control" id="name" placeholder="Your Name" data-rule="minlen:4" data-msg="Please enter at least 4 chars" />
</div>
<div>
<label for="email">Email</label>
<input type="email" class="form-control" name="user_email" id="user_email" placeholder="Your Email" data-rule="email" data-msg="Please enter a valid email" />
</div>
<div>
<label for="message">message:</label>
<textarea class="form-control" name="message" id="message" rows="5" data-rule="required" data-msg="Please write something" placeholder="Message"></textarea>
</div>
<div>
<input type="submit" value="Submit" />
</div>
</form>
</body>
</html>最简单的方法是基于表单元素的required属性提供仅HTML的解决方案，因为浏览器还将通过其元素/控件type接管所需元素的验证。。。
<form id="myForm" method="post" role="form" class="contactForm" action="https://stackoverflow.com/">
<input
required
type="text" name="name" id="name"
class="form-control" placeholder="Your Name"
/>
<input
required
type="email" name="email" id="email"
class="form-control" placeholder="Your Email"
/>
<textarea
required
name="message" id="message"
class="form-control" rows="5" placeholder="Message"></textarea>
<button
type="submit" id="submitFormData"
class="button button-a button-big button-rouded">Send Message</button>
</form>通用自定义验证要复杂得多，而且劳动密集。。。
function validateControValue(elm) {
let isValid = true;
const elmType = elm.type;
if (elmType !== 'button' && elmType !== 'submit') {
const $elm = $(elm);
const isEmpty = ($elm.val().trim() === '');
if (isEmpty) {
$elm.val('');
$elm.addClass('validation-error');
} else {
$elm.removeClass('validation-error');
}
// non empty is valid, empty is invalid.
isValid = !isEmpty;
}
return isValid;
}
function handleValidFormSubmit(/* evt */) {
const isValidSubmitData = Array
.from(this.elements)
.every(validateControValue);
return isValidSubmitData;
}
function main() {
$('#myForm').on('submit', handleValidFormSubmit)
}
$(document)
.ready(main);.validation-error {
border: 1px solid #f00;
}<form id="myForm" method="post" role="form" class="contactForm" action="https://stackoverflow.com/">
<input
type="text" name="name" id="name"
class="form-control" placeholder="Your Name"
/>
<input
type="email" name="email" id="email"
class="form-control" placeholder="Your Email"
/>
<textarea
name="message" id="message"
class="form-control" rows="5" placeholder="Message"></textarea>
<button
type="submit" id="submitFormData"
class="button button-a button-big button-rouded">Send Message</button>
</form>
<script src="http://code.jquery.com/jquery-latest.js"></script>
<!-- <script src="alert.js"></script> //-->