Bootstrap表单控件

Bootstrap表单控件是一种扩展了我们用类重置的表单样式的工具，它提供了许多用于自定义显示的选项，以便在浏览器和设备之间实现更一致的呈现。这些控件包括文本输入框、文本区域、复选框、单选按钮和下拉菜单等，它们都可以通过Bootstrap的样式进行定制和扩展。

一、示例

下面是一个演示 Bootstrap 表单样式的简单示例。

<form>
<div class="form-group">
<label for="exampleInputEmail1">Email address</label>
<input type="email" class="form-control" id="exampleInputEmail1" aria-describedby="emailHelp">
<small id="emailHelp" class="form-text text-muted">We'll never share your email with anyone else.</small>
</div>
<div class="form-group">
<label for="exampleInputPassword1">Password</label>
<input type="password" class="form-control" id="exampleInputPassword1">
</div>
<div class="form-group form-check">
<input type="checkbox" class="form-check-input" id="exampleCheck1">
<label class="form-check-label" for="exampleCheck1">Check me out</label>
</div>
<button type="submit" class="btn btn-primary">Submit</button>

二、表单控件

文本表单控件（如<input>、<select> 和<textarea>）使用.form-control类设置样式。包括一般外观、焦点状态、大小等样式。

<form>
<div class="form-group">
<label for="exampleFormControlInput1">Email address</label>
<input type="email" class="form-control" id="exampleFormControlInput1" placeholder="name@example.com">
</div>
<div class="form-group">
<label for="exampleFormControlSelect1">Example select</label>
<select class="form-control" id="exampleFormControlSelect1">
<option>1</option>
<option>2</option>
<option>3</option>
<option>4</option>
<option>5</option>
</select>
</div>
<div class="form-group">
<label for="exampleFormControlSelect2">Example multiple select</label>
<select multiple class="form-control" id="exampleFormControlSelect2">
<option>1</option>
<option>2</option>
<option>3</option>
<option>4</option>
<option>5</option>
</select>
</div>
<div class="form-group">
<label for="exampleFormControlTextarea1">Example textarea</label>
<textarea class="form-control" id="exampleFormControlTextarea1" rows="3"></textarea>
</div>
</form>

对于文件输入，请将 for ..form-control.form-control-file

<form>
<div class="form-group">
<label for="exampleFormControlFile1">Example file input</label>
<input type="file" class="form-control-file" id="exampleFormControlFile1">
</div>
</form>

三、大小

使用诸如.form-control-lg 和 .form-control-sm之类的类设置高度。

<input class="form-control form-control-lg" type="text" placeholder=".form-control-lg">
<input class="form-control" type="text" placeholder="Default input">
<input class="form-control form-control-sm" type="text" placeholder=".form-control-sm">

<select class="form-control form-control-lg">
<option>Large select</option>
</select>
<select class="form-control">
<option>Default select</option>
</select>
<select class="form-control form-control-sm">
<option>Small select</option>
</select>

四、只读

在输入上添加readonly 属性以防止修改输入的值。只读输入看起来更轻（就像禁用的输入一样），但保留标准光标

<input class="form-control" type="text" placeholder="Readonly input here..." readonly>

五、只读纯文本

如果要将表单中的<input readonly> 元素设置为纯文本样式，请使用.form-control-plaintext纯文本类删除默认表单字段样式并保留正确的边距和填充。

<form>
<div class="form-group row">
<label for="staticEmail" class="col-sm-2 col-form-label">Email</label>
<div class="col-sm-10">
<input type="text" readonly class="form-control-plaintext" id="staticEmail" value="email@example.com">
</div>
</div>
<div class="form-group row">
<label for="inputPassword" class="col-sm-2 col-form-label">Password</label>
<div class="col-sm-10">
<input type="password" class="form-control" id="inputPassword">
</div>
</div>
</form>

<form class="form-inline">
<div class="form-group mb-2">
<label for="staticEmail2" class="sr-only">Email</label>
<input type="text" readonly class="form-control-plaintext" id="staticEmail2" value="email@example.com">
</div>
<div class="form-group mx-sm-3 mb-2">
<label for="inputPassword2" class="sr-only">Password</label>
<input type="password" class="form-control" id="inputPassword2" placeholder="Password">
</div>
<button type="submit" class="btn btn-primary mb-2">Confirm identity</button>
</form>

六、范围输入

使用.form-control-range可以设置水平滚动的范围输入。

<form>
<div class="form-group">
<label for="formControlRange">Example Range input</label>
<input type="range" class="form-control-range" id="formControlRange">
</div>
</form>

七、复选框和单选按钮

默认复选框和单选按钮在.form-check的帮助下得到了改进，这两种输入类型的单个类改进了其 HTML 元素的布局和行为。

1、默认

默认情况下，任意数量的直系同级复选框和无线电都将垂直堆叠，并用.form-check适当间隔。

<div class="form-check">
<input class="form-check-input" type="checkbox" value="" id="defaultCheck1">
<label class="form-check-label" for="defaultCheck1">
Default checkbox
</label>
</div>
<div class="form-check">
<input class="form-check-input" type="checkbox" value="" id="defaultCheck2" disabled>
<label class="form-check-label" for="defaultCheck2">
Disabled checkbox
</label>
</div>

<div class="form-check">
<input class="form-check-input" type="radio" name="exampleRadios" id="exampleRadios1" value="option1" checked>
<label class="form-check-label" for="exampleRadios1">
Default radio
</label>
</div>
<div class="form-check">
<input class="form-check-input" type="radio" name="exampleRadios" id="exampleRadios2" value="option2">
<label class="form-check-label" for="exampleRadios2">
Second default radio
</label>
</div>
<div class="form-check">
<input class="form-check-input" type="radio" name="exampleRadios" id="exampleRadios3" value="option3" disabled>
<label class="form-check-label" for="exampleRadios3">
Disabled radio
</label>
</div>

2、内嵌

通过将复选框或单选按钮添加到任何 .form-check-inline.form-check。

<div class="form-check form-check-inline">
<input class="form-check-input" type="checkbox" id="inlineCheckbox1" value="option1">
<label class="form-check-label" for="inlineCheckbox1">1</label>
</div>
<div class="form-check form-check-inline">
<input class="form-check-input" type="checkbox" id="inlineCheckbox2" value="option2">
<label class="form-check-label" for="inlineCheckbox2">2</label>
</div>
<div class="form-check form-check-inline">
<input class="form-check-input" type="checkbox" id="inlineCheckbox3" value="option3" disabled>
<label class="form-check-label" for="inlineCheckbox3">3 (disabled)</label>
</div>

<div class="form-check form-check-inline">
<input class="form-check-input" type="radio" name="inlineRadioOptions" id="inlineRadio1" value="option1">
<label class="form-check-label" for="inlineRadio1">1</label>
</div>
<div class="form-check form-check-inline">
<input class="form-check-input" type="radio" name="inlineRadioOptions" id="inlineRadio2" value="option2">
<label class="form-check-label" for="inlineRadio2">2</label>
</div>
<div class="form-check form-check-inline">
<input class="form-check-input" type="radio" name="inlineRadioOptions" id="inlineRadio3" value="option3" disabled>
<label class="form-check-label" for="inlineRadio3">3 (disabled)</label>
</div>

3、无标签

添加到没有任何标签文本的输入中。请记住，仍要为辅助技术提供某种形式的辅助名称（例如，使用.position-static.form-checkaria-label）。

<div class="form-check">
<input class="form-check-input position-static" type="checkbox" id="blankCheckbox" value="option1" aria-label="...">
</div>
<div class="form-check">
<input class="form-check-input position-static" type="radio" name="blankRadio" id="blankRadio1" value="option1" aria-label="...">
</div>