Jquery方法addClass、removeClass有一个字体图标的问题

Question

我有一个固定位置的一排发-角-双下。

<!-- Intro Section -->
<section id="intro" class="intro-section">
   <div class="container">
    <div class="row row-fixed">
        <a  class="page-scroll " href="#about">
          <i class="fa fa-angle-double-down hvr-buzz"></i>
        </a>
   </div>
</section>

向下滚动时，a链接中href属性的fa-angle-double-down替换为fa-angle-double-up，带有remove/addClass等。

$(window).scroll(function() {
if ($(".navbar").offset().top > 50) {
    $(".navbar-fixed-top").addClass("top-nav-collapse");
    $(".intro-section .container .row-fixed .page-scroll i").removeClass('fa fa-angle-double-down hvr-buzz');
    $(".intro-section .container .row-fixed .page-scroll i").addClass('fa fa-angle-double-up hvr-buzz');
    $(".intro-section .container .row-fixed a").attr("href", "#page-top");
} else {
    $(".navbar-fixed-top").removeClass("top-nav-collapse");
    $(".intro-section .container .row-fixed .page-scroll i").addClass('fa fa-angle-double-down hvr-buzz');
    $(".intro-section .container .row-fixed .page-scroll i").removeClass('fa fa-angle-double-up hvr-buzz');
    $(".intro-section .container .row-fixed a").attr("href", "#about");
}

})；

好的，一切正常，但是当转到顶部时，在一个或多个向下滚动之后，fa fa-angle-double-down出现，但作为一个小块，具有fa-angle-double-down的行为，但外观不同。

为什么？

Answer 1

我是这样解决的：

$(window).scroll(function() {

if ($(".navbar").offset().top > 50) {
    $(".navbar-fixed-top").addClass("top-nav-collapse");
    $(".intro-section .container .row-fixed .page-scroll i").removeClass();
    $(".intro-section .container .row-fixed .page-scroll i").addClass('fa fa-angle-double-up hvr-buzz');
    $(".intro-section .container .row-fixed .page-scroll .fa-angle-double-up").css("color","#000");
    $(".intro-section .container .row-fixed a").attr("href", "#page-top");
} else {
    $(".navbar-fixed-top").removeClass("top-nav-collapse");
    $(".intro-section .container .row-fixed .page-scroll i").removeClass();
    $(".intro-section .container .row-fixed .page-scroll i").addClass('fa fa-angle-double-down hvr-buzz');
    $(".intro-section .container .row-fixed .page-scroll .fa-angle-double-down").css("color","#FFF");
    $(".intro-section .container .row-fixed a").attr("href", "#about");
}

})；

只是需要一点耐心