我希望在导航栏折叠时让搜索栏可见。

我的代码:http://jsfiddle.net/edalzell/a3yng825/1/折叠时有效，但展开时显示两个搜索栏。

HTML:

<header class= "blog-masthead"> 
    <nav class="navbar" role="navigation"> 
        <div class="container"> 
            <div class="navbar-header"> 
                <button type="button" class="navbar-toggle collapsed pull-left" data-toggle="collapse" data-target="#navbar-collapse"> 
                    <span class="sr-only">Toggle navigation</span> 
                    <span class="icon-bar"></span> 
                    <span class="icon-bar"></span> 
                    <span class="icon-bar"></span> 
                </button> 
                <form class="navbar-form collapsed navbar-right" role="search" action="/search" method="get"> 
                    <div class="form-group input-group"> 
                        <input type="text" class="form-control input-sm" placeholder="Search" id="sitesearch" name="query"> 
                        <span class="input-group-addon"><button type="submit" class="btn btn-default btn-xs"><span class="glyphicon glyphicon-search"></span></button></span> 
                    </div> 
                </form> 
            </div> <!-- navbar-header --> 
            <div class="collapse navbar-collapse" id="navbar-collapse"> 
                <ul class="nav navbar-nav navbar-left"> 
                    <li><a href="/blog">Blog</a></li> 
                    <li><a href="/about">About</a></li> 
 
                </ul> 
            <form class="navbar-form navbar-right" role="search" action="/search" method="get"> 
                <div class="form-group input-group"> 
                    <input type="text" class="form-control input-sm" placeholder="Search" id="sitesearch" name="query"> 
                    <span class="input-group-addon"><button type="submit" class="btn btn-default btn-xs"><span class="glyphicon glyphicon-search"></span></button></span> 
                </div> 
            </form> 
            </div> <!-- navbar-collapse --> 
        </div> 
    </nav> 
</header> 

请您参考如下方法:

这是因为您声明了两个搜索栏，因此您有几个选项来获得所需的结果

1. 删除您在折叠中声明的额外搜索栏 部分

2. 根据您想要的分辨率隐藏/显示特定元素，您可以查看 this SO thread

我用的是第一种方式，可以找到jsfiddle here

完整代码:

<header class= "blog-masthead"> 
    <nav class="navbar" role="navigation"> 
        <div class="container"> 
            <div class="navbar-header"> 
                <button type="button" class="navbar-toggle collapsed pull-left" data-toggle="collapse" data-target="#navbar-collapse"> 
                    <span class="sr-only">Toggle navigation</span> 
                    <span class="icon-bar"></span> 
                    <span class="icon-bar"></span> 
                    <span class="icon-bar"></span> 
                </button> 
                <form class="navbar-form collapsed navbar-right" role="search" action="/search" method="get"> 
                    <div class="form-group input-group"> 
                        <input type="text" class="form-control input-sm" placeholder="Search" id="sitesearch" name="query"> 
                        <span class="input-group-addon"><button type="submit" class="btn btn-default btn-xs"><span class="glyphicon glyphicon-search"></span></button></span> 
                    </div> 
                </form> 
            </div> <!-- navbar-header --> 
            <div class="collapse navbar-collapse" id="navbar-collapse"> 
                <ul class="nav navbar-nav navbar-left"> 
                    <li><a href="/blog">Blog</a></li> 
                    <li><a href="/about">About</a></li> 
 
                </ul> 
 
            </div> <!-- navbar-collapse --> 
        </div> 
    </nav> 
</header>