Bootstrap 滾動監聽(Scrollspy)
position: relative;
}
</style>
</head>
<body data-spy="scroll" data-target=".navbar" data-offset="50">
<nav class="navbar navbar-expand-sm navbar-dark fixed-top">
<ul class="nav justify-content-center">
<li class="nav-item">
<a class="nav-link" href="#section1">京東</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#section2">網易</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#section3">百度</a>
</li>
<li class="nav-item dropdown">
<a class="nav-link dropdown-toggle" href="#" id="navbardrop" data-toggle="dropdown">
騰訊
</a>
<div class="dropdown-menu">
<a class="dropdown-item" href="#section41">騰訊網</a>
<a class="dropdown-item" href="#section42">QQ音樂</a>
</div>
</li>
</ul>
</nav>
<div id="section1" class="container-fluid " style="padding-top:70px;padding-bottom:70px">
<h1>Section 1</h1>
<p>Try to scroll this section and look at the navigation bar while scrolling! Try to scroll this section and look at the navigation bar while scrolling!</p>
<p>Try to scroll this section and look at the navigation bar while scrolling! Try to scroll this section and look at the navigation bar while scrolling!</p>
</div>
<div id="section2" class="container-fluid bg-warning" style="padding-top:70px;padding-bottom:70px">
<h1>Section 2</h1>
<p>Try to scroll this section and look at the navigation bar while scrolling! Try to scroll this section and look at the navigation bar while scrolling!</p>
<p>Try to scroll this section and look at the navigation bar while scrolling! Try to scroll this section and look at the navigation bar while scrolling!</p>
</div>
<div id="section3" class="container-fluid bg-secondary" style="padding-top:70px;padding-bottom:70px">
<h1>Section 3</h1>
<p>Try to scroll this section and look at the navigation bar while scrolling! Try to scroll this section and look at the navigation bar while scrolling!</p>
<p>Try to scroll this section and look at the navigation bar while scrolling! Try to scroll this section and look at the navigation bar while scrolling!</p>
</div>
<div id="section41" class="container-fluid bg-danger" style="padding-top:70px;padding-bottom:70px">
<h1>Section 4 Submenu 1</h1>
<p>Try to scroll this section and look at the navigation bar while scrolling! Try to scroll this section and look at the navigation bar while scrolling!</p>
<p>Try to scroll this section and look at the navigation bar while scrolling! Try to scroll this section and look at the navigation bar while scrolling!</p>
</div>
<div id="section42" class="container-fluid " style="padding-top:70px;padding-bottom:70px" >
<h1>Section 4 Submenu 2</h1>
<p>Try to scroll this section and look at the navigation bar while scrolling! Try to scroll this section and look at the navigation bar while scrolling!</p>
<p>Try to scroll this section and look at the navigation bar while scrolling! Try to scroll this section and look at the navigation bar while scrolling!</p>
</div>
</body>
</html>
向您想要監聽的元素（通常是 body）新增 data-spy="scroll" 。
然後新增 data-target 屬性，它的值為導航欄的 id 或 class (.navbar)。這樣就可以聯絡上可滾動區域。
注意可滾動項元素上的 id （<div id="section1">） 必須匹配導航欄上的連結選項 （<a href="#section1">)。
可選項data-offset 屬性用於計算滾動位置時，距離頂部的偏移畫素。 預設為 10 px。
設定相對定位: 使用 data-spy="scroll" 的元素需要將其 CSS position 屬性設定為 "relative" 才能起作用。
以下例項設定了垂直滾動監聽：
body {
position: relative;
}
ul.nav-pills {
top: 20px;
position: fixed;
}
div.col-8 div {
height: 500px;
}
</style>
</head>
<body data-spy="scroll" data-target="#myScrollspy" data-offset="1">
<div class="container-fluid">
<div class="row">
<nav class="col-sm-3 col-4" id="myScrollspy">
<ul class="nav nav-pills flex-column">
<li class="nav-item">
<a class="nav-link active" href="#section1">Section 1</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#section2">Section 2</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#section3">Section 3</a>
</li>
<li class="nav-item dropdown">
<a class="nav-link dropdown-toggle" data-toggle="dropdown" href="#">Section 4</a>
<div class="dropdown-menu">
<a class="dropdown-item" href="#section41">Link 1</a>
<a class="dropdown-item" href="#section42">Link 2</a>
</div>
</li>
</ul>
</nav>
<div class="col-sm-9 col-8">
<div id="section1" class="bg-success">
<h1>Section 1</h1>
<p>Try to scroll this section and look at the navigation list while scrolling!</p>
</div>
<div id="section2" class="bg-warning">
<h1>Section 2</h1>
<p>Try to scroll this section and look at the navigation list while scrolling!</p>
</div>
<div id="section3" class="bg-secondary">
<h1>Section 3</h1>
<p>Try to scroll this section and look at the navigation list while scrolling!</p>
</div>
<div id="section41" class="bg-danger">
<h1>Section 4-1</h1>
<p>Try to scroll this section and look at the navigation list while scrolling!</p>
</div>
<div id="section42" class="bg-info">
<h1>Section 4-2</h1>
<p>Try to scroll this section and look at the navigation list while scrolling!</p>
</div>
</div>
</div>
</div>
