给网站添加一个自定义图片的 back to top 按钮

shopify 官方教程地址：https://help.shopify.com/themes/ ... -back-to-top-button

• **Online Store **> Themes.
• Actions > Edit code.
• 点击 Snippets 文件夹.
• 点击Add a new snippet.
• 命名为 back-to-the-top.
• 复制以下内容到 刚新建的文档中：记得替换https://cdn.shopify.com/your-image-url-btm.png为自己的图片地址**

{% comment %}
  Reduce below value if you need the back to the top button to appear higher up on the page.
  That value is in pixels.
{% endcomment %}
{% assign vertical_offset_for_trigger = 300 %}
{% comment %}
  Vertical offset from bottom of browser for the position of the button.
{% endcomment %}
{% assign position_from_bottom = '15em' %}
<a href="#" title="Back to the top" class="back-to-top">

<style>
.back-to-top:before {
    content: url(https://cdn.shopify.com/your-image-url-btm.png) !important;  
}
.back-to-top {
  position: fixed;
  bottom: {{position_from_bottom}};
  right: 0px;
  text-decoration: none;
  color: #999;
  background-color: #eee;
  font-size: 16px;
  padding: 0.3em;
  display: none;
  -webkit-border-top-left-radius: 3px;
  -webkit-border-bottom-left-radius: 3px;
  -moz-border-radius-topleft: 3px;
  -moz-border-radius-bottomleft: 3px;
  border-top-left-radius: 3px;
  border-bottom-left-radius: 3px;
  z-index: 60000;
}
.back-to-top i {
  vertical-align: middle;
}
.back-to-top span {
  padding-left: 0.5em;
}
.back-to-top i + span {
  padding-left: 0;
}
.back-to-top:hover {
  text-decoration: none;
  color: #555;
}
</style>
<script>
window.onload = function() {
jQuery(function($) {
   var offset = {{vertical_offset_for_trigger}};
   var duration = 500;
   $(window).scroll(function() {
     if ($(this).scrollTop() > offset) {
       $('.back-to-top').fadeIn(duration);
     }
     else {
       $('.back-to-top').fadeOut(duration);
     }
   });
   $('.back-to-top').unbind('click.smoothscroll').bind('click', function(e) {
     e.preventDefault();
     $('html, body').animate( { scrollTop: 0 }, duration);
     return false;
   })
});
}
</script>

点击保存
找到Layouts 文件夹， 打开 theme.liquid.
复制{% include 'back-to-the-top' %} 粘贴到</body> tag前面
点击保存。

如果你不喜欢有背景， 将background-color: #eee; 修改为background-color: transparent;
{% assign position_from_bottom = '4em' %} 修改4em的大小调整按钮离底部的距离， 数字越大按钮越高。