javascript - 如何创建粘性导航栏 css 和 javascript

Question

我正在尝试使用 CSS 和 JavaScript 在滚动时制作一个粘性导航栏，但它显示为普通导航栏，并且在滚动时不粘。滚动时如何让它粘住？我在代码中添加了标题

window.onscroll = function() {
  myFunction()
};

var navbar = document.getElementById("navbar");
var sticky = navbar.offsetTop;

function myFunction() {
  if (window.pageYOffset >= sticky) {
    navbar.classList.add("sticky")
  } else {
    navbar.classList.remove("sticky");
  }
}

#navbar {
  overflow: hidden;
  background-color: #333;
}


/* Navbar links */

#navbar a {
  float: left;
  display: block;
  color: #f2f2f2;
  text-align: center;
  padding: 14px;
  text-decoration: none;
}

.sticky {
  position: fixed;
  top: 0;
  width: 100%;
}

.sticky+.content {
  padding-top: 60px;
}

<div class="header">
	<h2>S I U</h2>
	<p>T h e  f u t u r e  &  B e y o n d</p>
</div>

<div id="navbar">
  <a href="#home">Home</a>
  <a href="#news">News</a>
  <a href="#contact">Contact</a>
</div>

Answer 1

快到了!您需要将 .sticky 类应用到您的导航，以使其固定。

window.onscroll = function() { myFunction() };
var navbar = document.getElementById("navbar");
var sticky = navbar.offsetTop;

function myFunction() {
    if (window.pageYOffset >= sticky) {
        navbar.classList.add("sticky")
    } else {
        navbar.classList.remove("sticky");
    }
}

body {
   height: 10000px;
}

#navbar {
  overflow: hidden;
  background-color: #333;
}


/* Navbar links */

#navbar a {
  float: left;
  display: block;
  color: #f2f2f2;
  text-align: center;
  padding: 14px;
  text-decoration: none;
}

.sticky {
  position: fixed;
  top: 0;
  width: 100%;
}

.sticky+.content {
  padding-top: 60px;
}

<div class="header">
  <h2>Scroll Down</h2>
  <p>Scroll down to see the sticky effect.</p>
</div>

<div id="navbar">
  <a href="#home">Home</a>
  <a href="#news">News</a>
  <a href="#contact">Contact</a>
</div>