MUI 返回顶部

        //绑定滚动到顶部按钮事件
        if ($("#scroll-up").length > 0) {

            var scrollToTopBox = $("#scroll-up"), isVisible = false;
            $(window).on("scroll.btnScrollTop", function() {
                var scroll = $(window).scrollTop(), h = $(window).height(), sh = document.body.scrollHeight;
                if (scroll > parseInt(h / 4) || (scroll > 0 && sh >= h && h + scroll >= sh - 1)) {
                    if (!isVisible) {
                        scrollToTopBox.addClass("display");
                        isVisible = true
                    }
                } else {
                    if (isVisible) {
                        scrollToTopBox.removeClass("display");
                        isVisible = false
                    }
                }
            }).triggerHandler("scroll.btnScrollTop");
            mui('body').on('tap', '#scroll-up', function(e) {
                e.stopPropagation();
                window.scrollTo(0, 0, 100);
             
                 
            })
        }

<a id="scroll-up" href="#" class="btn btn-sm">
        <span class="mui-icon mui-icon-arrowup"></span>
    </a>

CSS

#scroll-up {
    border-width: 0;
    position: fixed;
    right: 2px;
    z-index: 99;
    -webkit-transition-duration: .3s;
    transition-duration: .3s;
    opacity: 0;
    filter: alpha(opacity=0);
    bottom: -24px;
    visibility: hidden;
    background-color: #aaa;
    color: #fff;
    font-size: 14px
}

#scroll-up.display {
    opacity: .7;
    filter: alpha(opacity=70);
    bottom: 2px;
    visibility: visible
}

#scroll-up:hover {
    opacity: 1;
    filter: alpha(opacity=100)
}

#scroll-up:focus {
    outline: 0
}

其中字体文件需要替换为例自己的ttf文件，另外在

 <span class="mui-icon mui-icon-arrowup"></span>
里面的class也修改为例想要的即可，实测Android IOS 均可