附加类删除

从 Bootstrap 4 中删除了词缀。

建议使用 position: sticky polyfill 代替。

如果你使用 Affix 应用其他非位置样式，则 polyfill 可能不支持你的用例。此类用途的一个选项是第三方 ScrollPos-Styler 库。

根据 Bootstrap 文档

删掉了 Affix jQuery 插件。我们建议使用位置：粘性 polyfill。有关详细信息和特定的 polyfill 建议，请参阅 HTML5 Please 条目。

如果你使用 Affix 应用其他非位置样式，则 polyfill 可能不支持你的用例。此类用途的一个选项是第三方 ScrollPos-Styler 库。

如果有人从 Bootstrap v3 迁移到 Bootstrap v4，则会给出后备方法 -

HTML

<header>
    
</header>
<nav class="navbar navbar-light bg-faded" data-toggle="affix">
    <button class="navbar-toggler hidden-sm-up pull-xs-right" type="button" data-toggle="collapse" data-target="#collapsingNavbar">
        ☰
    </button>
    <a class="navbar-brand" href="#">Brand</a>
    <div class="collapse navbar-toggleable-xs" id="collapsingNavbar">

        <ul class="nav navbar-nav pull-xs-right">
            <li class="nav-item dropdown">
                <a class="nav-link dropdown-toggle" data-toggle="dropdown" href="#" role="button" aria-haspopup="true" aria-expanded="false">
                    Menu
                </a>
                <div class="dropdown-menu" aria-labelledby="Preview">
                    <a class="dropdown-item" href="">Logout</a>

                </div>
            </li>
            <li class="nav-item">
                <a class="nav-link" href="#">Link</a>
            </li>
            <li class="nav-item ">
                <a class="nav-link" href="#">Link</a>
            </li>
            <li class="nav-item ">
                <a class="nav-link" href="#">Link</a>
            </li>
        </ul>
    </div>
</nav>

<div class="container" id="main">
    <h2>Hello Bootstrap 4.</h2>
    <div class="row">
        <div class="col-xs-12 col-sm-6 col-md-9">
            <p>3 wolf moon retro jean shorts chambray sustainable roof party. Shoreditch vegan artisan Helvetica. Tattooed Codeply Echo Park Godard kogi, next level irony ennui twee squid fap selvage. Meggings flannel Brooklyn literally small batch, mumblecore
                PBR try-hard kale chips. Brooklyn vinyl lumbersexual bicycle rights, viral fap cronut leggings squid chillwave pickled gentrify mustache. 3 wolf moon hashtag church-key Odd Future. Austin messenger bag normcore, Helvetica Williamsburg
                sartorial tote bag distillery Portland before they sold out gastropub taxidermy Vice.</p>
        </div>
        <div class="col-xs-6 col-md-3">
            <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Duis pharetra codeply varius quam sit amet vulputate. Quisque mauris augue, molestie tincidunt codeply condimentum vitae, gravida a libero. Aenean sit amet felis dolor, in sagittis nisi.
                Sed ac orci quis tortor imperdiet venenatis. Duis elementum auctor accumsan. Aliquam in felis sit amet augue.
            </p>
            <hr>
            <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Duis pharetra codeply varius quam sit amet vulputate. Quisque mauris augue, molestie tincidunt codeply condimentum vitae, gravida a libero. Aenean sit amet felis dolor, in sagittis nisi.
                Sed ac orci quis tortor imperdiet venenatis. Duis elementum auctor accumsan. Aliquam in felis sit amet augue.
            </p>
        </div>
    </div>
    <div class="row">
        <div class="col-xs-6 col-sm-4">
            <div class="card card-outline-primary">
               <div class="card-block">
               <h3 class="card-title">Card</h3>
                <p class="card-text">With supporting text below as a natural lead-in to additional content.</p>
                    <a href="#" class="btn btn-outline-secondary">Outline</a>
                </div>
            </div>
        </div>
        <div class="col-xs-6 col-sm-4">
            <div class="card card-outline-primary">
               <div class="card-block">
               <h3 class="card-title">Card</h3>
                <p class="card-text">With supporting text below as a natural lead-in to additional content.</p>
                    <a href="#" class="btn btn-outline-secondary">Outline</a>
                </div>
            </div>
        </div>
        <div class="col-xs-6 col-sm-4">
            <div class="card card-outline-primary">
               <div class="card-block">
               <h3 class="card-title">Card</h3>
                <p class="card-text">With supporting text below as a natural lead-in to additional content.</p>
                    <a href="#" class="btn btn-outline-secondary">Outline</a>
                </div>
            </div>
        </div>
    </div>
</div>

CSS

header {
height: 220px;
background: #ccc;
}

JAVASCRIPT

$(document).ready(function() {

  var toggleAffix = function(affixElement, scrollElement, wrapper) {
  
    var height = affixElement.outerHeight(),
        top = wrapper.offset().top;
    
    if (scrollElement.scrollTop() >= top){
        wrapper.height(height);
        affixElement.addClass("affix");
    }
    else {
        affixElement.removeClass("affix");
        wrapper.height('auto');
    }
      
  };
  

  $('[data-toggle="affix"]').each(function() {
    var ele = $(this),
        wrapper = $('<div></div>');
    
    ele.before(wrapper);
    $(window).on('scroll resize', function() {
        toggleAffix(ele, $(this), wrapper);
    });
    
    // init
    toggleAffix(ele, $(window), wrapper);
  });
  
});