如果我的输入类型编号字段超过一个，我只想在我的文件提交按钮上添加必需的属性。
我在google上搜索过，我尝试了一些代码但没有工作，有人能指导我正确的方向吗？
$(document).ready(function(){
$('input[name="reg"]').change(function () {
if($("#reg").is('>1')) {
$('#up').attr('required', true);
} else {
$('#up').removeAttr('required');
}
});
});<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css" rel="stylesheet" />
<!DOCTYPE html>
<html>
<head>
<title>Test</title>
</head>
<style type="text/css">
</style>
<body>
<div class="container">
<form method="post">
<div class="form-group">
<label>Registrations</label>
<div class="input-group">
<input required="" type="number" class="form-control" name="reg" id="reg" value="" />
</div>
</div>
<div class="form-group">
<div class="input-group">
<input type="file" name="upload" id="up">
</div>
</div>
<input type="submit" name="submit" value="submit" class="btn btn-primary">
</form>
</div>
</body>
</html>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/js/bootstrap.min.js"></script>
<!-- begin snippet: js hide: false console: true babel: false -->
答案 0 :(得分：3)
$(document).ready(function() {
$('input[name="reg"]').change(function() {
if ($(this).val() > 1) {
$('#up').attr('required', true);
alert('Error')
} else {
$('#up').removeAttr('required');
}
console.log($("#up").attr("required"));
});
});<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css" rel="stylesheet" />
<!DOCTYPE html>
<html>
<head>
<title>Test</title>
</head>
<style type="text/css">
</style>
<body>
<div class="container">
<form method="post">
<div class="form-group">
<label>Registrations</label>
<div class="input-group">
<input required="" type="number" class="form-control" name="reg" id="reg" value="" />
</div>
</div>
<div class="form-group">
<div class="input-group">
<input type="file" name="upload" id="up">
</div>
</div>
<input type="submit" name="submit" value="submit" class="btn btn-primary">
</form>
</div>
</body>
</html>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/js/bootstrap.min.js"></script>
<!-- begin snippet: js hide: false console: true babel: false -->
答案 1 :(得分：2)
而不是$("#reg").is('>1')你应该使用
$(this).val() > 1
$(document).ready(function() {
$('input[name="reg"]').change(function() {
if ($(this).val() > 1) {
$('#up').attr('required', true);
} else {
$('#up').removeAttr('required');
}
console.log($("#up").attr("required"));
});
});<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css" rel="stylesheet" />
<!DOCTYPE html>
<html>
<head>
<title>Test</title>
</head>
<style type="text/css">
</style>
<body>
<div class="container">
<form method="post">
<div class="form-group">
<label>Registrations</label>
<div class="input-group">
<input required="" type="number" class="form-control" name="reg" id="reg" value="" />
</div>
</div>
<div class="form-group">
<div class="input-group">
<input type="file" name="upload" id="up">
</div>
</div>
<input type="submit" name="submit" value="submit" class="btn btn-primary">
</form>
</div>
</body>
</html>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/js/bootstrap.min.js"></script>
<!-- begin snippet: js hide: false console: true babel: false -->
答案 2 :(得分：2)
您需要检查输入值：
$(document).ready(function(){
$('input[name="reg"]').change(function () {
if($("#reg").val() > 1) {
$('#up').attr('required', true);
} else {
$('#up').removeAttr('required');
}
});
});<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css" rel="stylesheet" />
<!DOCTYPE html>
<html>
<head>
<title>Test</title>
</head>
<style type="text/css">
</style>
<body>
<div class="container">
<form method="post">
<div class="form-group">
<label>Registrations</label>
<div class="input-group">
<input required="" type="number" class="form-control" name="reg" id="reg" value="" />
</div>
</div>
<div class="form-group">
<div class="input-group">
<input type="file" name="upload" id="up">
</div>
</div>
<input type="submit" name="submit" value="submit" class="btn btn-primary">
</form>
</div>
</body>
</html>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/js/bootstrap.min.js"></script>
<!-- begin snippet: js hide: false console: true babel: false -->
答案 3 :(得分：0)
使用$("#reg").val() > 1 val（）给出您输入的文本框的值
$(document).ready(function(){
$('input[name="reg"]').change(function () {
if($("#reg").val() > 1) {
$('#up').attr('required', true);
} else {
$('#up').removeAttr('required');
}
});
});<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css" rel="stylesheet" />
<!DOCTYPE html>
<html>
<head>
<title>Test</title>
</head>
<style type="text/css">
</style>
<body>
<div class="container">
<form method="post">
<div class="form-group">
<label>Registrations</label>
<div class="input-group">
<input required="" type="number" class="form-control" name="reg" id="reg" value="" />
</div>
</div>
<div class="form-group">
<div class="input-group">
<input type="file" name="upload" id="up">
</div>
</div>
<input type="submit" name="submit" value="submit" class="btn btn-primary">
</form>
</div>
</body>
</html>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/js/bootstrap.min.js"></script>
<!-- begin snippet: js hide: false console: true babel: false -->