bootstrap导航栏.nav与.navbar区别

刚刚看了bootstrap的导航栏，发现有点弄混了，如今来整理一下；

1、简单的ul,li组成的导航：

<ul class="nav nav-pills justify-content-center bg-dark nav-dark">
        <li class="nav-item">
            <a href="#" class="nav-link">1</a>
        </li>
        <li class="nav-item">
            <a href="#" class="nav-link">2</a>
        </li>
        <li class="nav-item">
            <a href="#" class="nav-link">3</a>
        </li>
    </ul>

//解析：.nav .nav-item .nav-link表示ul li是导航——.nav-pills表示胶囊状导航——.bg-dark/.nav-dark表示黑底白字——.justify-content-center表示导航栏在浏览器上居中显示

在浏览器上显示为：

缩小浏览器窗口显示为：

2、导航栏——<nav>标签中class="navbar navbar-expand-sm"——<ul>中class="navbar-nav"——<li>中class="nav-item"

代码为：

<nav class="navbar navbar-expand-sm bg-dark navbar-dark">
    <ul class="navbar-nav">
        <li class="nav-item active">
            <a href="#" class="nav-link">link1</a>
        </li>
        <li class="nav-item">
            <a href="#" class="nav-link">link1</a>
        </li>
        <li class="nav-item">
            <a href="#" class="nav-link">link1</a>
        </li>
        <li class="nav-item">
            <a href="#" class="nav-link">link1</a>
        </li>    
    </ul>
</nav>

正常窗口显示为：

 

缩小窗口小于576px时：

3、折叠导航栏

当窗口小于576px的时候，不单单是简单的编程垂直导航；显示为一个button按钮，导航连接隐藏，点击button显示；

 代码为：

<nav class="navbar navbar-expand-sm bg-dark navbar-dark fixed-top">
    <a href="#" class="navbar-brand">
            <img src="" alt="logo" style="width:70px;height:30px;">
    </a>
    <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#collapsible">
        <span class="navbar-toggler-icon"></span>
    </button>
    <div class="collapse navbar-collapse" id="collapsible">
    <ul class="navbar-nav">
        <li class="nav-item active">
            <a href="#" class="nav-link">link1</a>
        </li>
        <li class="nav-item">
            <a href="#" class="nav-link">link1</a>
        </li>
        <li class="nav-item">
            <a href="#" class="nav-link">link1</a>
        </li>
        <li class="nav-item">
            <a href="#" class="nav-link">link1</a>
        </li>    
    </ul>
    
</nav>

//注意：.navbar-brand是品牌logo；

窗口大于576的时候，显示为：

窗口小于576的时候，显示为：

　

4、导航栏加上form表单表示搜索框：【？？？？？】

代码以下：

<nav class="navbar navbar-expand-sm bg-dark navbar-dark fixed-top">
    <a href="#" class="navbar-brand">
            <img src="" alt="logo" style="width:70px;height:30px;">
    </a>
    <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#collapsible">
        <span class="navbar-toggler-icon"></span>
    </button>
    <div class="collapse navbar-collapse" id="collapsible">
    <ul class="navbar-nav">
        <li class="nav-item active">
            <a href="#" class="nav-link">link1</a>
        </li>
        <li class="nav-item">
            <a href="#" class="nav-link">link1</a>
        </li>
        <li class="nav-item">
            <a href="#" class="nav-link">link1</a>
        </li>
        <li class="nav-item">
            <a href="#" class="nav-link">link1</a>
        </li>    
    </ul>
    <form class="form-inline">
                <div class="input-group">
                    <span class="input-group-addon">@</span>
                    <input list="dl" type="text" class="form-control" placeholder="Search"/>
                    <datalist id="dl">
                        <option value="IE"></option>
                        <option value="Firefox"></option>
                        <option value="chrome"></option>
                        <option value="safari"></option>
                    </datalist>
                </div>
                
                <button class="btn btn-success" type="submit">search</button>
            </form>
</nav>

 

如图所示，如何使得导航栏中的form表单右对齐，移到最右边？？？？？float：eight应该也行吧。。

 　　　　emmmm.....知道了上面的解决方法了：利用网格系统，将左边的ul,li和右边的form表单分别排列；.col-sm-6;而后再给form表单右浮动；

　　　　代码以下：

 1 <div class="container-fluid">
 2     <div class="row">
 3         <!-- 导航栏 -->
 4         <nav class="navbar fixed-top navbar-expand-sm bg-dark navbar-dark">
 5             <div class="col-lg-4">
 6             <ul class="navbar-nav">
 7                 <li class="nav-item">
 8                     <a class="nav-link" href="#">link1</a>
 9                 </li>
10                 <li class="nav-item">
11                     <a class="nav-link" href="#">link2</a>
12                 </li>
13                 <li class="nav-item">
14                     <a class="nav-link" href="#">link3</a>
15                 </li>
16             </ul>
17             </div>
18 <!-- 导航栏表单与按钮 -->
19         <div class="col-lg-8">
20             <form class="form-inline" style="float:right;">
21                 <div class="input-group">
23                     <span class="input-group-addon">@</span>
24                     <input list="dl" type="text" class="form-control" placeholder="Search"/>
25                     <datalist id="dl">
26                         <option value="IE"></option>
27                         <option value="Firefox"></option>
28                         <option value="chrome"></option>
29                         <option value="safari"></option>
30                     </datalist>
31                     <button class="btn btn-success" type="submit">search</button>
32                 </div>                            
33             </form>
34             </div>            
35         </nav>
36         </div>
37             </div>