Question

当用户向下滚动网站时，我试图让我的导航栏显示白色背景。但出于某种原因，我不确定如何让白色背景出现在导航栏上，一旦我滚动，我的一直在消失

所以我的导航栏显示正常，页面顶部没有背景。然后我需要的是，一旦用户向下滚动页面，它应该只是粘在屏幕顶部，背面有白色背景。

像这样：Example

但显然我已经设置了导航栏，我只需要背景显示

<body>
    <div class="parallax">
        <div class ="logo">
        <img src="Images/logo1.fw.png">
        </div> 

     <nav class="navbar navbar-default">
        <div class="container-fluid">
          <div class="navbar-header">
            <button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#navbar" aria-expanded="false" aria-controls="navbar">
              <span class="sr-only">Toggle navigation</span>
              <span class="icon-bar"></span>
              <span class="icon-bar"></span>
              <span class="icon-bar"></span>
            </button>
          </div>
          <div id="navbar" class="navbar-collapse collapse">
            <ul class="nav navbar-nav">
              <li><a href="#">Home</a></li>
              <li><a href="#">Timetable</a></li>
              <li><a href="#">Prices</a></li>
              <li><a href="#">About Us</a></li>
              <li><a href="#">Contact</a></li>
              <li><a href="#">Belt Rankings</a></li>
              <li><a href="#">Blog</a></li>
              <li class="dropdown">
                <a href="#" class="dropdown-toggle" data-toggle="dropdown" role="button" aria-haspopup="true" aria-expanded="false">Classes </a>
                <ul class="dropdown-menu">
                  <li><a href="#">Brazilian Jiu Jitsu</a></li>
                  <li><a href="#">Wrestling</a></li>
                  <li><a href="#">Boxing</a></li>
                  <li><a href="#">Yoga</a></li>
                  <li><a href="#">Women Self-Defence</a></li>
                  <li><a href="#">Treatments</a></li>
                  <li><a href="#">Kids</a></li>
                </ul>
              </li>
            </ul>
          </div><!--/.nav-collapse -->
        </div><!--/.container-fluid -->
      </nav>

          <div class="container">

        </div>





    </div>

    <div class="parallax1">
    </div>
          <!-- jQuery (necessary for Bootstrap's JavaScript plugins) -->
    <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js"></script>
    <!-- Include all compiled plugins (below), or include individual files as needed -->
    <script src="js/bootstrap.js"></script>
    <script>
  $(document).ready(function(){

    // hide .navbar first
    $(".navbar").show();

    // fade in .navbar
    $(function () {
        $(window).scroll(function () {

        $('.navbar-default').css({
          backgroundColor:  $(this).scrollTop() > 100 ? 
            'white':
            'transparent'
        })
        });


    });

});
      </script>
</body>

CSS：

body {
    font-family: 'Open Sans', sans-serif, Arial;
    font-size: 16px;
    color: #6D6D6D;
    background-color: #F5F5F5;
    font-weight: 300;
}
h1,h2,h3,h4,h5,h6 {
    font-family: 'Montserrat', sans-serif, Arial;

    padding-bottom: 5px;
    color: #373432;
    line-height: 1em;
    font-weight: normal;
}
a {
    text-decoration: none;
    outline: none;
}


.parallax {
    background-image: url("../Images/back1.jpg");
    min-height: 1000px;
    background-attachment: fixed;
    background-position: center;
    background-repeat: no-repeat;
    background-size: cover;
    width: 100%;
}

.parallax1 {
    min-height: 1000px;
}



.logo {
  float: left;
  padding-top: 50px;
  padding-left: 40px;   
}

.logo h1 {
    text-transform: uppercase;
    font-weight: 900;
    font-size: 60px;
    letter-spacing: -5px;
    line-height: 50px;
    color: white;
}

.navbar-nav>li>a {
    line-height: 6px;
}


.navbar {
  float: right;
  padding-top: 50px;
  padding-right: 60px;
  font-size: 13px;
      text-transform: uppercase;
}

.navbar-default {
    background-color: transparent;
    border-top: 0px solid rgba(0, 0, 0, 0.5);
    border-bottom: 0px solid rgba(0, 0, 0, 0.5);
    border-left: 0px solid rgba(0, 0, 0, 0.5);
    border-right: 0px solid rgba(0, 0, 0, 0.5);
      -webkit-transition: background-color 200ms linear;
  -moz-transition: background-color 200ms linear;
  -o-transition: background-color 200ms linear;
  -ms-transition: background-color 200ms linear;
  transition: background-color 200ms linear;
}

.navbar-default .navbar-nav>li>a {
    color: #ffffff;
}

.navbar-default .navbar-nav > li > a:hover, 
.navbar-default .navbar-nav > li > a:focus {
      background-color: #F8BD23;
      text-decoration: none;
       color: #ffffff;
    -webkit-transition: background-color 200ms linear;
    -moz-transition: background-color 200ms linear;
    -o-transition: background-color 200ms linear;
    -ms-transition: background-color 200ms linear;
    transition: background-color 200ms linear;
    }

    .navbar-nav > li{
  padding-left:30px;

}

.container {
  width:100%;
  height:100%;
  display:flex;
  justify-content:center;
  flex-direction: column;
  align-items: center;
}

Answer 1

原则上，您需要更改：

...
if ($(this).scrollTop() > 100) {
  $('.navbar').fadeIn();
} else {
  $('.navbar').fadeOut();
}
...

...到......

...
$('.navbar-default').css({
  backgroundColor:  $(this).scrollTop() > 100 ? 
    'white':
    'transparent'
})
...

您可能还想在CSS中为background-color .navbar-default属性添加转换，就像您为链接所做的那样：

.navbar-default {
  -webkit-transition: background-color 200ms linear;
  -moz-transition: background-color 200ms linear;
  -o-transition: background-color 200ms linear;
  -ms-transition: background-color 200ms linear;
  transition: background-color 200ms linear;
}

在实践中，您希望将其包含在一个不仅仅是scroll事件调用的函数中。也就是load和resize事件，例如：

var checkScrollBar = function(){
  $('.navbar-default').css({
    backgroundColor: $(this).scrollTop() > 100 ?
      'white' : 'transparent'
  })
}
$(window).on('load resize scroll', checkScrollBar)

工作示例：

var checkScrollBar = function(){
  $('.navbar-default').css({
    backgroundColor: $(this).scrollTop() > 100 ?
      'white' : 'transparent'
  })
}
$(window).on('load resize scroll', checkScrollBar)

body {
  margin:0
}
body > div {
  background-color: red;
}
.parallax1 {
  min-height: 200vh;
}

/* 
 * all CSS above is just for for SO, don't use in project 
 */

nav.navbar-default {
  background-color: transparent;
  transition: background-color 200ms linear;
}

<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet"/>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
  
  <div class="parallax">
    <div class="logo">
      <img src="Images/logo1.fw.png">
    </div>
    <nav class="navbar navbar-default navbar-fixed-top">
      <div class="container-fluid">
        <div class="navbar-header">
          <button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#navbar" aria-expanded="false" aria-controls="navbar">
              <span class="sr-only">Toggle navigation</span>
              <span class="icon-bar"></span>
              <span class="icon-bar"></span>
              <span class="icon-bar"></span>
            </button>
        </div>
        <div id="navbar" class="navbar-collapse collapse">
          <ul class="nav navbar-nav">
            <li><a href="#">Home</a></li>
            <li><a href="#">Timetable</a></li>
            <li><a href="#">Prices</a></li>
            <li><a href="#">About Us</a></li>
            <li><a href="#">Contact</a></li>
            <li><a href="#">Belt Rankings</a></li>
            <li><a href="#">Blog</a></li>
            <li class="dropdown">
              <a href="#" class="dropdown-toggle" data-toggle="dropdown" role="button" aria-haspopup="true" aria-expanded="false">Classes </a>
              <ul class="dropdown-menu">
                <li><a href="#">Brazilian Jiu Jitsu</a></li>
                <li><a href="#">Wrestling</a></li>
                <li><a href="#">Boxing</a></li>
                <li><a href="#">Yoga</a></li>
                <li><a href="#">Women Self-Defence</a></li>
                <li><a href="#">Treatments</a></li>
                <li><a href="#">Kids</a></li>
              </ul>
            </li>
          </ul>
        </div>
        <!--/.nav-collapse -->
      </div>
      <!--/.container-fluid -->
    </nav>
    <div class="container">
    </div>
  </div>
  <div class="parallax1">
    
  </div>

获取导航栏以滚动显示白色背景

1 个答案: