jQuery - "fadeIn is not a function"
The default template for Bootstrap 4 uses th "slim" version of jQuery which doesn't include many functions. You need to switch back to using a more featured version. For example:
body {
display:none;
}<!DOCTYPE html>
<html lang="en">
<head>
<!-- Required meta tags -->
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
<!-- Bootstrap CSS -->
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta/css/bootstrap.min.css" integrity="sha384-/Y6pD6FV/Vv2HJnA6t+vslU6fwYXjCFtcEpHbNJ0lyAFsXTsjBbfaDjzALeQsN6M" crossorigin="anonymous">
<link rel="stylesheet" href="css/custom.css">
</head>
<body>
Test
<!-- Optional JavaScript -->
<!-- jQuery first, then Popper.js, then Bootstrap JS -->
<script src="https://code.jquery.com/jquery-3.2.1.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.11.0/umd/popper.min.js" integrity="sha384-b/U6ypiBEHpOf/4+1nzFpr53nxSS+GLCkfwBdFNTxtclqqenISfwAzpKaMNFNmj4" crossorigin="anonymous"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta/js/bootstrap.min.js" integrity="sha384-h0AbiXch4ZDo7tp9hKZ4TsHbi047NrKGLO3SEJAg45jXxnGIfYzk4Si90RDIqNm1" crossorigin="anonymous"></script>
<script type="text/javascript">
$(document).ready(function(){
$('body').fadeIn();
})
</script>
</body>
</html>The slim version is enough with a small CSS:
jQuery("#toTop").addClass('fade-in');
and
.fade-in {
opacity: 1;
animation-name: fadeInOpacity;
animation-iteration-count: 1;
animation-timing-function: ease-in;
animation-duration: 0.5s;
}
@keyframes fadeInOpacity {
0% {
opacity: 0;
}
100% {
opacity: 1;
}
}