Bootstrap4 表单

在本章中，我们将学习如何使用 Bootstrap 创建表单。Bootstrap 通过一些简单的 HTML 标签和扩展的类即可创建出不同样式的表单。

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表单元素 <input>, <textarea>, 和 <select> elements 在使用 .form-control 类的情况下，宽度都是设置为 100%。

Bootstrap4 表单布局

• 堆叠表单 (全屏宽度)：垂直方向
• 内联表单：水平方向

Bootstrap 提供了两种类型的表单布局:

堆叠表单

以下实例使用两个输入框，一个复选框，一个提交按钮来创建堆叠表单：

实例

<
form

action
=
"
"
>

<
div

class
=
"
form-group
"
>

<
label

for
=
"
email
"
>
Email address:
</
label
>

<
input

type
=
"
email
"

class
=
"
form-control
"

placeholder
=
"
Enter email
"

id
=
"
email
"
>

</
div
>

<
div

class
=
"
form-group
"
>

<
label

for
=
"
pwd
"
>
Password:
</
label
>

<
input

type
=
"
password
"

class
=
"
form-control
"

placeholder
=
"
Enter password
"

id
=
"
pwd
"
>

</
div
>

<
div

class
=
"
form-group form-check
"
>

<
label

class
=
"
form-check-label
"
>

<
input

class
=
"
form-check-input
"

type
=
"
checkbox
"
>
Remember me
</
label
>

</
div
>

<
button

type
=
"
submit
"

class
=
"
btn btn-primary
"
>
Submit
</
button
>

</
form
>

尝试一下 »

显示效果：

内联表单

所有内联表单中的元素都是左对齐的。

注意：在屏幕宽度小于 576px 时为垂直堆叠，如果屏幕宽度大于等于576px时表单元素才会显示在同一个水平线上。

内联表单需要在 <form> 元素上添加 .form-inline类。

以下实例使用两个输入框，一个复选框，一个提交按钮来创建内联表单：

实例

<
form

class
=
"
form-inline
"
>

<
label

for
=
"
email
"
>
Email address:
</
label
>

<
input

type
=
"
email
"

class
=
"
form-control
"

id
=
"
email
"
>

<
label

for
=
"
pwd
"
>
Password:
</
label
>

<
input

type
=
"
password
"

class
=
"
form-control
"

id
=
"
pwd
"
>

<
div

class
=
"
form-check
"
>

<
label

class
=
"
form-check-label
"
>

<
input

class
=
"
form-check-input
"

type
=
"
checkbox
"
>
Remember me
</
label
>

</
div
>

<
button

type
=
"
submit
"

class
=
"
btn btn-primary
"
>
Submit
</
button
>

</
form
>

尝试一下 »

显示效果：

上面的实例元素排列看起来很紧凑，可以使用 .mr-sm-2 类来设置右边距，使用.mb-2 类设置底部边距：

实例

<
form

class
=
"
form-inline
"

action
=
"
"
>

<
label

for
=
"
email
"

class
=
"
mr-sm-2
"
>
Email address:
</
label
>

<
input

type
=
"
email
"

class
=
"
form-control mb-2 mr-sm-2
"

placeholder
=
"
Enter email
"

id
=
"
email
"
>

<
label

for
=
"
pwd
"

class
=
"
mr-sm-2
"
>
Password:
</
label
>

<
input

type
=
"
password
"

class
=
"
form-control mb-2 mr-sm-2
"

placeholder
=
"
Enter password
"

id
=
"
pwd
"
>

<
div

class
=
"
form-check mb-2 mr-sm-2
"
>

<
label

class
=
"
form-check-label
"
>

<
input

class
=
"
form-check-input
"

type
=
"
checkbox
"
>
Remember me
</
label
>

</
div
>

<
button

type
=
"
submit
"

class
=
"
btn btn-primary mb-2
"
>
Submit
</
button
>

</
form
>

尝试一下 »

显示效果：

表单行/网格

我们还可以使用 .col 类来控制表单元素的宽度和对齐方式，不需要使用间距类。 .col 类来控制的表单需要放在 .row 容器中。

以下实例将两个列并排显示：

实例

<
form
>

<
div

class
=
"
row
"
>

<
div

class
=
"
col
"
>

<
input

type
=
"
text
"

class
=
"
form-control
"

id
=
"
email
"

placeholder
=
"
Enter email
"

name
=
"
email
"
>

</
div
>

<
div

class
=
"
col
"
>

<
input

type
=
"
password
"

class
=
"
form-control
"

placeholder
=
"
Enter password
"

name
=
"
pswd
"
>

</
div
>

</
div
>

</
form
>

尝试一下 »

显示效果：

如果网格要使用比较小的间距可以使用 .form-row 替代 .row:

实例

<
form
>

<
div

class
=
"
form-row
"
>

<
div

class
=
"
col
"
>

<
input

type
=
"
text
"

class
=
"
form-control
"

id
=
"
email
"

placeholder
=
"
Enter email
"

name
=
"
email
"
>

</
div
>

<
div

class
=
"
col
"
>

<
input

type
=
"
password
"

class
=
"
form-control
"

placeholder
=
"
Enter password
"

name
=
"
pswd
"
>

</
div
>

</
div
>

</
form
>

尝试一下 »

表单验证

我们可以使用不同的验证类来设置表单的验证功能。

.was-validated 或 .needs-validation 添加到 <form> 元素中，input 输入字段将具有绿色（有效）或红色（无效）边框效果，用于说明表单是否需要输入内容。

.valid-feedback 或 .invalid-feedback 类用来告诉用户缺少什么信息，或者在提交表单之前需要完成什么。

实例

使用 .was-validated 类显示表单在提交之前需要填写的内容：

<
form

action
=
"
"

class
=
"
was-validated
"
>

<
div

class
=
"
form-group
"
>

<
label

for
=
"
uname
"
>
Username:
</
label
>

<
input

type
=
"
text
"

class
=
"
form-control
"

id
=
"
uname
"

placeholder
=
"
Enter username
"

name
=
"
uname
"

required
>

<
div

class
=
"
valid-feedback
"
>
验证成功！
</
div
>

<
div

class
=
"
invalid-feedback
"
>
请输入用户名！
</
div
>

</
div
>

<
div

class
=
"
form-group
"
>

<
label

for
=
"
pwd
"
>
Password:
</
label
>

<
input

type
=
"
password
"

class
=
"
form-control
"

id
=
"
pwd
"

placeholder
=
"
Enter password
"

name
=
"
pswd
"

required
>

<
div

class
=
"
valid-feedback
"
>
验证成功！
</
div
>

<
div

class
=
"
invalid-feedback
"
>
请输入密码！
</
div
>

</
div
>

<
div

class
=
"
form-group form-check
"
>

<
label

class
=
"
form-check-label
"
>

<
input

class
=
"
form-check-input
"

type
=
"
checkbox
"

name
=
"
remember
"

required
>
同意协议
<
div

class
=
"
valid-feedback
"
>
验证成功！
</
div
>

<
div

class
=
"
invalid-feedback
"
>
同意协议才能提交。
</
div
>

</
label
>

</
div
>

<
button

type
=
"
submit
"

class
=
"
btn btn-primary
"
>
提交
</
button
>

</
form
>

尝试一下 »

实例

使用 .needs-validation，它将在表单提交之后验证缺少的内容。这里需要添加一些 JavaScript 代码才能使代码正常工作：

<
form

action
=
"
"

class
=
"
needs-validation
"

novalidate
>

<
div

class
=
"
form-group
"
>

<
label

for
=
"
uname
"
>
Username:
</
label
>

<
input

type
=
"
text
"

class
=
"
form-control
"

id
=
"
uname
"

placeholder
=
"
Enter username
"

name
=
"
uname
"

required
>

<
div

class
=
"
valid-feedback
"
>
验证成功！
</
div
>

<
div

class
=
"
invalid-feedback
"
>
请输入用户名！
</
div
>

</
div
>

<
div

class
=
"
form-group
"
>

<
label

for
=
"
pwd
"
>
Password:
</
label
>

<
input

type
=
"
password
"

class
=
"
form-control
"

id
=
"
pwd
"

placeholder
=
"
Enter password
"

name
=
"
pswd
"

required
>

<
div

class
=
"
valid-feedback
"
>
验证成功！
</
div
>

<
div

class
=
"
invalid-feedback
"
>
请输入密码！
</
div
>

</
div
>

<
div

class
=
"
form-group form-check
"
>

<
label

class
=
"
form-check-label
"
>

<
input

class
=
"
form-check-input
"

type
=
"
checkbox
"

name
=
"
remember
"

required
>
同意协议
<
div

class
=
"
valid-feedback
"
>
验证成功！
</
div
>

<
div

class
=
"
invalid-feedback
"
>
同意协议才能提交。
</
div
>

</
label
>

</
div
>

<
button

type
=
"
submit
"

class
=
"
btn btn-primary
"
>
提交
</
button
>

</
form
>

<
script
>
// 如果验证不通过禁止提交表单 (function() { 'use strict'; window.addEventListener('load', function() { // 获取表单验证样式 var forms = document.getElementsByClassName('needs-validation'); // 循环并禁止提交 var validation = Array.prototype.filter.call(forms, function(form) { form.addEventListener('submit', function(event) { if (form.checkValidity() === false) { event.preventDefault(); event.stopPropagation(); } form.classList.add('was-validated'); }, false); }); }, false); })();
</
script
>

尝试一下 »