Google AMP - 数据绑定

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amp-bind 帮助通过数据绑定和类似 JS 的表达式，根据操作为 amp 组件和 html 标签添加交互性。本章详细讨论数据绑定。

要使用 amp-bind，我们需要将以下脚本添加到我们的页面中：

<script async custom-element = "amp-bind" 
   src = "https://cdn.ampproject.org/v0/amp-bind-0.1.js">
</script>

让我们借助一个工作示例来全面理解这一点，如下所示：

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 - Amp Bind</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>
      <style amp-custom>
         button{ 
            background-color: #ACAD5C; 
            color: white; 
            padding: 12px 20px; 
            border: none; 
            border-radius: 4px; 
         }
      </style>
   </head>
   <body>
      <h3>Google AMP - Amp Bind</h3>
      <p [text] = "'Hello ' + world + '.'">
         Click on the button to change the text
      </p>
      <button on = "tap:AMP.setState({world: 'This is amp-bind example'})">
      Click Here
      </button>
   </body>
</html>

输出

Data binding

单击按钮以查看文本更改，如下所示：

Amp Data binding

因此，在上面显示的示例中，我们使用了 amp-bind 来更改单击按钮时的文本。

Amp-bind 有三个组件：

  • 状态 - 最初状态为空。单击按钮后，状态会更改。例如，

<button on = "tap:AMP.setState({world: 'This is amp-bind example'})">
   Click Here
</button>

AMP.setState 方法用于更改状态。变量 world 被赋值为 This is amp-bind example。变量 world 用于 html 标签中：

<p [text] = "'Hello ' + world + '.'">
   Click on the button to change the text
</p>

单击按钮时，world 被赋予一个新值：This is amp-bind example。

我们还可以将 amp-state 与绑定一起使用，如下所示：

<amp-state id = "myState">
   <script type = "application/json">
      {
         "foo": "bar"
      }
   </script>
</amp-state>

表达式将在绑定期间被赋值为 bmyState.foo。

  • 表达式 - amp-bind 工作的表达式如下所示：

'Hello ' + world

world 被称为状态变量。

  • 绑定 - 绑定应用于 [属性] 形式的特殊属性。例如：

<p [text] = "'Hello ' + world + '.'">
   Click on the button to change the text
</p>

在上面的示例中，[text] 具有用于绑定 p 标签的表达式。

我们可以使用以下属性进行绑定：

  • [text]
  • [class]
  • [hidden]
  • [width]
  • [height]

绑定也可以在 amp 组件上执行，并且仅允许特定属性。以下列表显示了此类组件和属性：

序号 Amp 组件 属性 & 描述
1 <amp-carousel type=slides> [slide]*

使用此绑定行为更改幻灯片
2 <amp-date-picker> [min]

min -> 设置最早可选日期

[max]

max -> 设置最晚可选日期
3 <amp-iframe> [src]

更改 iframe 的 src
4 <amp-img> [alt] [attribution] [src] [srcset]

我们可以更改 alt、attribution、src 和 srcset。如果更改了 src，请更改 srcset，因为它用于缓存
5 <amp-lightbox> [open]*

您可以通过绑定到 open 来显示/隐藏灯箱
6 <amp-list> [src]

如果表达式是字符串，则从字符串 URL 获取并呈现 JSON。如果表达式是对象或数组，则呈现表达式数据。
7 <amp-selector> [selected]* [disabled]

更改当前选定的子元素，这些元素由其 option 属性值标识。支持逗号分隔的值列表以进行多选

使用 Amp-State 进行绑定

我们可以使用 amp-state 定义所有我们想要在 html 元素或 amp 组件上使用的数据。

amp-state 中使用的数据必须采用 json 格式，如下所示：

<amp-state id = "myCarsList">
   <script type = "application/json">
      {
         "currentcar" : "bmw",
         "audi": {
            "imageUrl": "images/audi.jpg"
         },
         "bmw": {
            "imageUrl": "images/bmw.jpg"
         }
      }
   </script>
</amp-state>

因此，我们定义了键值对，其中包含汽车的名称和用于汽车的图像。

文本上的 Amp-bind 和 Amp-Image

下面显示了一个使用 amp-state 和 amp-bind 的工作示例：

<!doctype html>
<html amp lang = "en">
   <head>
      <meta charset = "utf-8">
      <script async src = "https://cdn.ampproject.org/v0.js"></script>
      <title>Google AMP - Amp Bind</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>
      <style amp-custom>
         button{ 
            background-color: #ACAD5C; 
            color: white; 
            padding: 12px 20px; 
            border: none; 
            border-radius: 4px; 
            cursor: pointer; 
            float: left;
         }
      </style>
   </head>
   <body>
      <h3>Google AMP - Amp Bind</h3>
      <amp-state id = "myCarsList">
         <script type = "application/json">
            {
               "currentcar" : "bmw",
               "audi": {
               "imageUrl": "images/audi.jpg",
               "style": "greenBackground"
               },
               "bmw": {
               "imageUrl": "images/bmw.jpg",
               "style": "redBackground"
               }
            }
         </script>
      </amp-state>
      <amp-img 
         width = "300" 
         height = "200" 
         src = "images/bmw.jpg" 
         [src] = "myCarsList[currentcar].imageUrl">
      </amp-img>
      <p [text] = "'This is a ' + currentcar + '.'">
         This is a BMW.
      </p>
      <br/>
      <button on = "tap:AMP.setState({currentcar: 'audi'})">
         Change Car
      </button>
   </body>
</html>

输出

Amp Image Text

单击按钮以查看汽车图像和下面的文本更改。

Amp Image Texts

视频和内嵌框架上的 Amp-bind

我们现在将看到一个工作示例，该示例将更改 amp-iframe 和 amp-video 的 src。

<!doctype html>
<html amp lang = "en">
   <head>
      <meta charset = "utf-8">
      <script async src = "https://cdn.ampproject.org/v0.js"></script>
      <title>Google AMP - Amp Bind</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-video" src =
         "https://cdn.ampproject.org/v0/amp-video-0.1.js"></script>
      <script async custom-element = "amp-iframe" src =
         "https://cdn.ampproject.org/v0/amp-iframe-0.1.js"></script>
      <style amp-custom>
         button{ 
            background-color: #ACAD5C; 
            color: white; 
            padding: 12px 20px; 
            border: none; 
            border-radius: 4px; 
            cursor: pointer; 
            float: left;
         }
      </style>
   </head>
   <body>
      <h3>Google AMP - Amp Bind</h3>
      <button on = "tap:AMP.setState({currentlist: 'list1'})">
      Click Here
      </button>
      <br/>
      <br/>
      <amp-state id = "myList">
         <script type = "application/json">
            {
               "currentlist" : "",
               "list1": {
                  "url": "video/m.mp4",
                  "style": "greenBackground",
                  "iframeurl":"https://maps.google.com/maps?q=hyderabad&t=&z=13&ie=UTF8&iwloc=&output=embed"
               }
            }
         </script>
      </amp-state>
      <h3>AMP - IFRAME</h3>
      <amp-iframe 
         width = "600"
         title = "Google map"
         height = "400"
         layout = "responsive"
         sandbox = "allow-scripts allow-same-origin allow-popups"
         frameborder = "0"
         src = "https://maps.google.com/maps?q=telangana&t=&z=13&ie=UTF8&iwloc=&output=embed"
         [src] = "myList[currentlist].iframeurl">
         <amp-img 
            layout = "fill" 
            src = "images/loading.jpg" 
            placeholder
            >
         /amp-img>
      </amp-iframe>
      <h3>AMP - VIDEO</h3>
      <amp-video 
         id = "amp-video" 
         src = "video/samplevideo.mp4" 
         layout="responsive" 
         [src] = "myList[currentlist].url" 
         width = "300" 
         height = "170" autoplay controls>
      </amp-video>
   </body>
</html>

请注意，这里我们使用了带有 iframesrc 和视频 src 的 amp-state。

<amp-state id = "myList">
   <script type = "application/json">
      {
         "currentlist" : "",
         "list1": {
            "url": "video/m.mp4",
            "style": "greenBackground",
            "iframeurl":"
            https://maps.google.com/maps?q=hyderabad&t=&z=13&ie=UTF8&iwloc=&output=embed"
         }
      }
   </script>
</amp-state>

currentlist 设置为空，点击按钮后，它被设置为 list1。currentlist 变量用于 iframe 和视频的 src，如下所示：

<amp-iframe width="600"
   title = "Google map"
   height = "400"
   layout = "responsive"
   sandbox = "allow-scripts allow-same-origin allow-popups"
   frameborder = "0" src = "https://maps.google.com/maps?q=telangana&t=&z=13&ie=UTF8&iwloc=&output=embed"
   [src] = "myList[currentlist].iframeurl">
      <amp-img layout = "fill" src = "images/loading.jpg" placeholder>
      </amp-img>
</amp-iframe>
<amp-video id = "amp-video" src = "video/samplevideo.mp4" 
   layout = "responsive" [src] = "myList[currentlist].url" width = "300" 
   height = "170" autoplay controls>
</amp-video>

输出

Amp Video Iframe

单击按钮以查看视频和 iframe 的 src 更改。

Amp Video Iframe

带有 amp-lightbox 的 Amp-bind

现在，让我们看看绑定和 amp-lightbox 结合使用时的工作原理。

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 - Amp Bind</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-lightbox" src =
         "https://cdn.ampproject.org/v0/amp-lightbox-0.1.js"></script>
      <style amp-custom>
         button{ 
            background-color: #ACAD5C; 
            color: white; 
            padding: 12px 20px; 
            border: none; 
            border-radius: 4px; 
            cursor: pointer; 
            float: left;
         }
         .lightbox {
            background: rgba(211,211,211,0.8);
            width: 100%;
            height: 100%;
            position: absolute;
            display: flex;
            align-items: center;
            justify-content: center;
         }
      </style>
   </head>
   <body>
      <h3>Google AMP - Amp Bind</h3>
      <button on = "tap:AMP.setState({displaylightbox: true})">
      Click Here
      </button>
      <br/>
      <br/>
      <h3>AMP - Lightbox</h3>
      <amp-lightbox 
         id = "my-lightbox" 
         [open] = "displaylightbox" 
         layout = "nodisplay" 
         close-button>
         <div class = "lightbox" on = "tap:AMP.setState({displaylightbox: false})">
            <amp-img alt = "Beautiful Flower"
               src = "images/loreal.gif"
               width = "246"
               height = "205">
            </amp-img>
         </div>
      </amp-lightbox>
   </body>
</html>

要在 amp-lightbox 上使用绑定，我们已在 amp-lightbox 上使用了 [open]，如下所示：

<amp-lightbox id = "my-lightbox" [open] = "displaylightbox" 
   layout = "nodisplay" close-button>
   <div class = "lightbox" on="tap:AMP.setState({displaylightbox: false})">
      <amp-img alt = "Beautiful Flower"
         src = "images/loreal.gif"
         width = "246"
         height = "205">
      </amp-img>
   </div>
</amp-lightbox>

[open] = “displaylightbox” 是一个变量状态，在单击按钮和点击灯箱 div 时更改为 true/false：

<button on = "tap:AMP.setState({displaylightbox: true})">
   Click Here
</button>

<div class = "lightbox" on = "tap:AMP.setState({displaylightbox: false})">
   <amp-img alt = "Beautiful Flower"
      src = "images/loreal.gif"
      width = "246"
      height = "205">
   </amp-img>
</div>

输出

Amp Lightbox Bind

输入元素的 Amp 绑定

让我们借助一个工作示例来了解 amp 绑定到输入元素的工作原理，如下所示：

<!doctype html>
<html amp lang = "en">
   <head>
      <meta charset = "utf-8">
      <script async src = "https://cdn.ampproject.org/v0.js"></script>
      <title>Google AMP - Amp Bind</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-lightbox" 
            src = "https://cdn.ampproject.org/v0/amp-lightbox-0.1.js">
      </script>
      <style amp-custom>
         button{ 
            background-color: #ACAD5C; 
            color: white; 
            padding: 12px 20px; 
            border: none; 
            border-radius: 4px; 
            cursor: pointer; 
            float: left;
         }
         .lightbox {
            background: rgba(211,211,211,0.8);
            width: 100%;
            height: 100%;
            position: absolute;
            display: flex;
            align-items: center;
            justify-content: center;
         }
         #txtname{
            width: 100%;
            padding: 12px 20px;
            margin: 8px 0;
            display: inline-block;
            border: 1px solid #ccc;
            border-radius: 4px;
            box-sizing: border-box;
         }
         div {
            font-size:25px;
         }
      </style>
   </head>
   <body>
      <h3>Google AMP - Amp Bind</h3>
      <button on = "tap:AMP.setState({displaylightbox: true})">
         Click Here
      </button>
      <br/>
      <br/>
      <h3>
         AMP - Input Element
      <h3>
      <input id = "txtname" placeholder = "Type here" 
         on = "input-throttled:AMP.setState({name: event.value})">
      <div [text] = "name">
      </div>
   </body>
</html>

输出

Amp Input Element

在文本框中输入的数据显示在底部。可以通过在输入事件上更改状态变量 name 来实现，如下所示：

<input id = "txtname" placeholder = "Type here" on = 
"input-throttled:AMP.setState({name: event.value})">
<div [text] = "name">
</div>
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