.valid-feedback 或 .invalid-feedback 類用來(lái)告訴用戶缺少什么信息，或者在提交表單之前需要完成什么。

實(shí)例

使用 .was-validated 類顯示表單在提交之前需要填寫的內(nèi)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
"
>
驗(yàn)證成功！
div
>

<
div

class
=
"
invalid-feedback
"
>
請(qǐng)輸入用戶名！
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
"
>
驗(yàn)證成功！
div
>

<
div

class
=
"
invalid-feedback
"
>
請(qǐng)輸入密碼！
div
>

div
>

<
div

class
=
"
form-group form-check
"
>

<
label

class
=
"
form-check-label
"
>

<
input

class
=
"
form-check-input
"

type
=
"
checkbox
"

name
=
"
remember
"

required
>
同意協(xié)議
<
div

class
=
"
valid-feedback
"
>
驗(yàn)證成功！
div
>

<
div

class
=
"
invalid-feedback
"
>
同意協(xié)議才能提交。
div
>

label
>

div
>

<
button

type
=
"
submit
"

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

form
>

嘗試一下 ?

實(shí)例

使用 .needs-validation，它將在表單提交之后驗(yàn)證缺少的內(nèi)容。這里需要添加一些 JavaScript 代碼才能使代碼正常工作：

<
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
"
>
驗(yàn)證成功！
div
>

<
div

class
=
"
invalid-feedback
"
>
請(qǐng)輸入用戶名！
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
"
>
驗(yàn)證成功！
div
>

<
div

class
=
"
invalid-feedback
"
>
請(qǐng)輸入密碼！
div
>

div
>

<
div

class
=
"
form-group form-check
"
>

<
label

class
=
"
form-check-label
"
>

<
input

class
=
"
form-check-input
"

type
=
"
checkbox
"

name
=
"
remember
"

required
>
同意協(xié)議
<
div

class
=
"
valid-feedback
"
>
驗(yàn)證成功！
div
>

<
div

class
=
"
invalid-feedback
"
>
同意協(xié)議才能提交。
div
>

label
>

div
>

<
button

type
=
"
submit
"

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

form
>

<
script
>
// 如果驗(yàn)證不通過(guò)禁止提交表單 (function() { 'use strict'; window.addEventListener('load', function() { // 獲取表單驗(yàn)證樣式 var forms = document.getElementsByClassName('needs-validation'); // 循環(huán)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
>

嘗試一下 ?