在过渡中显示背景色

Question

我试图用一些动画来显示background-color，但它突然出现了。我希望导航栏background-color以某种动画形式出现。

JSFiddle演示：https://jsfiddle.net/3f0czkpt/

$(window).scroll(function() {
if ($(document).scrollTop() > 100) {
$('.navbar').addClass('affix');
} else {
$('.navbar').removeClass('affix');
}
});

body {
padding-top: 50px;
background-color: #eee;
}
.navbar {
-webkit-transition: padding 0.2s ease;
-moz-transition: padding 0.2s ease;
-o-transition: padding 0.2s ease;
transition: padding 0.2s ease;
}
.affix {
padding-top: 0.2em !important;
padding-bottom: 0.2em !important;
background-color: #000;
-webkit-transition: padding 0.2s linear;
-moz-transition: padding 0.2s linear;
-o-transition: padding 0.2s linear;
transition: padding background-color 0.2s linear;
}

<link href="https://stackpath.bootstrapcdn.com/bootstrap/4.4.1/css/bootstrap.min.css" rel="stylesheet"/>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<nav class="navbar navbar-expand-md navbar-dark fixed-top">
<a class="navbar-brand" href="#">Brand</a>
<button class="navbar-toggler navbar-toggler-right" type="button" data-toggle="collapse" data-target="#navbarCollapse" aria-controls="navbarCollapse" aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
<div class="collapse navbar-collapse" id="navbarCollapse">
<ul class="navbar-nav mr-auto">
<li class="nav-item active">
<a class="nav-link" href="#">Home <span class="sr-only">(current)</span></a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Link</a>
</li>
<li class="nav-item">
<a class="nav-link disabled" href="#" tabindex="-1" aria-disabled="true">Disabled</a>
</li>
</ul>
<form class="form-inline mt-2 mt-md-0">
<input class="form-control mr-sm-2" type="text" placeholder="Search" aria-label="Search">
<button class="btn btn-outline-success my-2 my-sm-0" type="submit">Search</button>
</form>
</div>
</nav>
<section>
<div class="container-fluid">
<h1>Here is some content</h1>
<p>Sriracha biodiesel taxidermy organic post-ironic, Intelligentsia salvia mustache 90's code editing brunch. Butcher polaroid VHS art party, hashtag Brooklyn deep v PBR narwhal sustainable mixtape swag wolf squid tote bag. Tote bag cronut semiotics,
raw denim deep v taxidermy messenger bag. Tofu YOLO Etsy, direct trade ethical Odd Future jean shorts paleo. Forage Shoreditch tousled aesthetic irony, street art organic Bushwick artisan cliche semiotics ugh synth chillwave meditation. Shabby chic
lomo plaid vinyl chambray Vice. Vice sustainable cardigan, Williamsburg master cleanse hella DIY 90's blog.</p>
<p>Ethical Kickstarter PBR asymmetrical lo-fi. Dreamcatcher street art Carles, stumptown gluten-free Kickstarter artisan Wes Anderson wolf pug. Godard sustainable you probably haven't heard of them, vegan farm-to-table Williamsburg slow-carb readymade
disrupt deep v. Meggings seitan Wes Anderson semiotics, cliche American Apparel whatever. Helvetica cray plaid, vegan brunch Banksy leggings +1 direct trade. Wayfarers codeply PBR selfies. Banh mi McSweeney's Shoreditch selfies, forage fingerstache
food truck occupy YOLO Pitchfork fixie iPhone fanny pack art party Portland.</p>
</div>
</section>
<section>
<div class="container-fluid">
<h1>Here is some more content</h1>
<h1>Here is some content</h1>
<p>Sriracha biodiesel taxidermy organic post-ironic, Intelligentsia salvia mustache 90's code editing brunch. Butcher polaroid VHS art party, hashtag Brooklyn deep v PBR narwhal sustainable mixtape swag wolf squid tote bag. Tote bag cronut semiotics,
raw denim deep v taxidermy messenger bag. Tofu YOLO Etsy, direct trade ethical Odd Future jean shorts paleo. Forage Shoreditch tousled aesthetic irony, street art organic Bushwick artisan cliche semiotics ugh synth chillwave meditation. Shabby chic
lomo plaid vinyl chambray Vice. Vice sustainable cardigan, Williamsburg master cleanse hella DIY 90's blog.</p>
<p>Ethical Kickstarter PBR asymmetrical lo-fi. Dreamcatcher street art Carles, stumptown gluten-free Kickstarter artisan Wes Anderson wolf pug. Godard sustainable you probably haven't heard of them, vegan farm-to-table Williamsburg slow-carb readymade
disrupt deep v. Meggings seitan Wes Anderson semiotics, cliche American Apparel whatever. Helvetica cray plaid, vegan brunch Banksy leggings +1 direct trade. Wayfarers codeply PBR selfies. Banh mi McSweeney's Shoreditch selfies, forage fingerstache
food truck occupy YOLO Pitchfork fixie iPhone fanny pack art party Portland.</p>
</div>
</section>

Answer 1

转换规则属于基类.navbar，而不是在达到滚动阈值后附加的类。另外，使用逗号分隔多个转换特性。

body {
padding-top: 50px;
background-color: #eee;
}
.navbar { 
transition: padding, background-color 0.2s linear;  
}
.affix {
padding-top: 0.2em !important;
padding-bottom: 0.2em !important;
background-color: #000;      
}

这是一个工作演示：jsFiddle