How to turn off if the mobile navbar is open when the page is scrolled? [closed]

问题

If the navigation bar is open in the mobile view of a website, how can I close the navigation bar when the page is scrolled? The easiest way (css or js)

回答1:

Well for me i would prefer to use JS. and here is an example i got from w3schools,which is working with both web and mobile views of navigation bar

var prevScrollpos = window.pageYOffset;
window.onscroll = function() {
  var currentScrollPos = window.pageYOffset;
  if (prevScrollpos > currentScrollPos) {
    document.getElementById("navbar").style.top = "0";
  } else {
    document.getElementById("navbar").style.top = "-50px";
  }
  prevScrollpos = currentScrollPos;
}

body {
  margin: 0;
  background-color: #f1f1f1;
  font-family: Arial, Helvetica, sans-serif;
}

#navbar {
  background-color: #333;
  position: fixed;
  top: 0;
  width: 100%;
  display: block;
  transition: top 0.3s;
}

#navbar a {
  float: left;
  display: block;
  color: #f2f2f2;
  text-align: center;
  padding: 15px;
  text-decoration: none;
  font-size: 17px;
}

#navbar a:hover {
  background-color: #ddd;
  color: black;
}

<body>

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

<div style="padding:15px 15px 2500px;font-size:30px;margin-top:30px;">
  <p><b>This example demonstrates how to hide a navbar when the user starts to scroll the page.</b></p>
  <p>Scroll down this frame to see the effect!</p>
  <p>Scroll up to show the navbar.</p>
  <p>Lorem ipsum dolor dummy text sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.</p>
  <p>Lorem ipsum dolor dummy text sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.</p>
</div>

</body>

来源：https://stackoverflow.com/questions/61648962/how-to-turn-off-if-the-mobile-navbar-is-open-when-the-page-is-scrolled

标签

javascript

html

jquery

css

bootstrap-4