Google AMP - 动态 CSS 类

amp-dynamic-css-classes 会向 body 标签添加动态类。本章我们将学习此标签的详细信息。

要使用 amp-dynamic-css-classes，我们需要添加以下脚本：

<script asynccustom-element="amp-dynamic-css-classes" 
   src = "https://cdn.ampproject.org/v0/amp-dynamic-css-classes-0.1.js">
</script>

amp-dynamic-css-classes 会处理两个重要的类：

amp-referrer-*
amp-viewer

让我们详细讨论每个类。

amp-referrer-*

这些类根据用户的访问来源设置。这意味着如果用户来自 Google，则会设置与 Google 相关的 referrer 类。Twitter 和 Pinterest 也同样适用。

这些类根据引荐来源的类型提供。

例如，如果用户从 Google 搜索引擎点击 AMP 页面，则会添加以下类：

amp-referrer-www-google-com
amp-referrer-google-com
amp-referrer-com

同样，Twitter、Pinterest、LinkedIn 等也有相应的类。

amp-viewer

AMP 查看器基本上会更改 AMP URL 以从 Google 缓存获取详细信息。如果您在 Google 搜索中搜索某些内容，显示的轮播将包含所有 AMP 页面。

单击这些页面后，它们会重定向到以 Google URL 为前缀的 URL。当用户在 AMP 查看器中查看页面并使用动态类时，将设置 amp-viewer 类。

单击 AMP 页面后，您在地址栏中获得的 URL 如下所示：

https://www.google.co.in/amp/s/m.timesofindia.com/sports/cricket/india-in-australia/to-hell-with-the-nets-boys-need-rest-ravi-shastri/amp_articleshow/67022458.cms

示例

<!doctype html>
<html amp lang = "en">
   <head>
      <meta charset =  "utf-8">
      <script async src = "https://cdn.ampproject.org/v0.js"></script>
      <title>Google AMP - Dynamic Css Classes</title>
      <link rel = "canonical" href = "http://example.ampproject.org/article-metadata.html">
      <meta name = "viewport" content = "width = device-width,minimum-scale = 1,initial-scale = 1">
      
      <style amp-boilerplate>
         body{
            -webkit-animation:
            -amp-start 8s steps(1,end) 0s 1 normal both;-moz-animation:
            -amp-start 8s steps(1,end) 0s 1 normal both;-ms-animation:
            -amp-start 8s steps(1,end) 0s 1 normal both;animation:
            -amp-start 8s steps(1,end) 0s 1 normal both
         }
         @-webkit-keyframes 
         -amp-start{from{visibility:hidden}to{visibility:visible}}@-moz-keyframes 
         -amp-start{from{visibility:hidden}to{visibility:visible}}@-ms-keyframes 
         -amp-start{from{visibility:hidden}to{visibility:visible}}@-o-keyframes 
         -amp-start{from{visibility:hidden}to{visibility:visible}}@keyframes 
         -amp-start{from{visibility:hidden}to{visibility:visible}}
      </style>
      
      <noscript>
         <style amp-boilerplate>
            body {
               -webkit-animation:none;-moz-animation:none;
               -ms-animation:none;animation:none
            }
         </style>
      </noscript>

      <script async custom-element = "amp-bind" 
         src = "https://cdn.ampproject.org/v0/amp-bind-0.1.js">
      </script>
      <script async custom-element = "amp-dynamic-css-classes" 
         src = "https://cdn.ampproject.org/v0/amp-dynamic-css-classes-0.1.js">
      </script>
      <link rel = "stylesheet" href = "https://cdnjs.cloudflare.com/ajax/libs/materialize/0.98.0/css/materialize.min.css">
      
      <style amp-custom>
         body:not(.amp-referrer-pinterest-com) .if-pinterest,
         body:not(.amp-referrer-ampbyexample-com) .if-ampbyexample,
         body:not(.amp-referrer-google-com) .if-google,
         body:not(.amp-referrer-twitter-com) .if-twitter,
         body:not(.amp-referrer-linkedin-com) .if-linkedin,
         body:not(.amp-referrer-localhost) .if-localhost {
            display: none;
         }
         body:not(.amp-viewer) .if-viewer,
            body.amp-viewer .if-not-viewer {
            display: none;
         }
         p {
            padding: 1rem;
            font-size:25px;
         }
      </style>
   </head>
   <body>
      <h3>Google AMP - Dynamic Css Classes</h3>
      <div>
      
         <p class = "if-pinterest">You were referred here or embedded by Pinterest!</p>
         <p class = "if-twitter">You were referred here or embedded by Twitter!</p>
         <p class = "if-google">You were referred here or embedded by Google!</p>
         <p class = "if-ampbyexample">You came here directly! Cool :)</p>
         < class = "if-localhost">You came here directly! Cool :)</p>
      </div>
      <div>
         <p class = "if-not-viewer">Hey! You are not coming from amp viewer</p>
         <p class = "if-viewer">Hey! From amp viewer.</p>
      <div>
   </body>
</html>

输出

打印页面