在水平滚动中固定bootstrap导航栏

<nav class="navbar navbar-expand-lg navbar-light bg-light">
  <a class="navbar-brand" href="#">Logo</a>
  <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarNav" aria-controls="navbarNav" aria-expanded="false" aria-label="Toggle navigation">
    <span class="navbar-toggler-icon"></span>
  </button>
  <div class="collapse navbar-collapse" id="navbarNav">
    <ul class="navbar-nav">
      <li class="nav-item active">
        <a class="nav-link" href="#">Home</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">About</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">Services</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">Contact</a>
      </li>
    </ul>
  </div>
</nav>

.navbar {
  position: fixed;
  width: 100%;
  top: 0;
  background-color: #fff;
  z-index: 100;
}

.navbar-scroll {
  overflow-x: auto;
  white-space: nowrap;
}

.navbar-nav {
  display: inline-block;
}

.nav-item {
  display: inline-block;
}

$(window).scroll(function() {
  var scroll = $(window).scrollTop();
  if (scroll >= 50) {
    $('.navbar').addClass('navbar-scroll');
  } else {
    $('.navbar').removeClass('navbar-scroll');
  }
});