Framework7 - 延遲載入

描述

延遲載入會延遲頁面上影像的載入過程。延遲載入可以提高滾動效能，加快頁面載入速度並節省流量。

要使延遲載入元素和影像正常工作，必須將其放在可滾動的<div class = "page-content">內。

下表演示了延遲載入的使用：

序號	延遲載入用法及說明
1	用法延遲載入可以應用於影像、背景影像以及漸入效果。
2	手動初始化延遲載入如果在初始化頁面後手動新增延遲載入影像，則延遲載入將不起作用，需要使用方法來初始化它。

可以使用延遲載入影像/元素上的lazy事件手動觸發影像載入，如下所示：

$$('img.lazy').trigger('lazy');

$$('div.lazy').trigger('lazy');

示例

以下示例演示了在 Framework7 中使用延遲載入：

<!DOCTYPE html>
<html class = "with-statusbar-overlay">

   <head>
      <meta name = "viewport" content = "width = device-width, initial-scale = 1, 
         maximum-scale = 1, minimum-scale = 1, user-scalable = no, minimal-ui" />
      <meta name = "apple-mobile-web-app-capable" content = "yes" />
      <meta name = "apple-mobile-web-app-status-bar-style" content = "black" />
      <title>Lazy Load</title>
      <link rel = "stylesheet" 
         href = "https://cdnjs.cloudflare.com/ajax/libs/framework7/1.4.2/css/framework7.ios.min.css" />
      <link rel = "stylesheet" 
         href = "https://cdnjs.cloudflare.com/ajax/libs/framework7/1.4.2/css/framework7.ios.colors.min.css" />
   </head>

   <body>
      <div class = "views">
         <div class = "view view-main">
            <div class = "pages">
               <div data-page = "home" class = "page navbar-fixed">
                  
                  <div class = "navbar">
                     <div class = "navbar-inner">
                        <div class = "left"> </div>
                        <div class = "center">Lazy Load</div>
                        <div class = "right"> </div>
                     </div>
                  </div>
                  
                  <div class = "page-content">
                     <div class = "content-block">
                        <div class = "content-block-inner">
                           <p> <img data-src = "/framework7/images/pic4.jpg" 
                              width = "100%" class = "lazy lazy-fadeIn"></p>
                           
                           <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit, 
                              sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. 
                              Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris 
                              nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in 
                              reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla 
                              pariatur.</p>
                           
                           <p> <img data-src = "/framework7/images/pic5.jpg" 
                              width = "100%" class = "lazy lazy-fadeIn"></p>
                              
                           <p>Sed ut perspiciatis unde omnis iste natus error sit 
                              voluptatem accusantium doloremque laudantium, totam rem aperiam, 
                              eaque ipsa quae ab illo inventore veritatis et quasi architecto 
                              beatae vitae dicta sunt explicabo. Nemo enim ipsam voluptatem quia 
                              voluptas sit aspernatur aut odit aut fugit, sed quia consequuntur 
                              magni dolores eos qui ratione voluptatem sequi nesciunt.</p>
                           
                           <p> <img data-src = "/framework7/images/background.jpg" 
                              width = "100%" class = "lazy lazy-fadeIn"></p>
                              
                           <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit, 
                              sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. 
                              Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris 
                              nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in 
                              reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla 
                              pariatur.</p>
                           
                           <p> <img data-src = "/framework7/images/pic6.jpg"
                              width = "100%" class = "lazy lazy-fadeIn"></p>
                              
                           <p>Sed ut perspiciatis unde omnis iste natus error sit voluptatem 
                              accusantium doloremque laudantium, totam rem aperiam, eaque ipsa quae ab 
                              illo inventore veritatis et quasi architecto beatae vitae dicta sunt 
                              explicabo. Nemo enim ipsam voluptatem quia voluptas sit aspernatur aut 
                              odit aut fugit, sed quia consequuntur magni dolores eos qui ratione 
                              voluptatem sequi nesciunt.</p>
                           
                           <p> <img data-src = "/framework7/images/pic7.jpg" 
                              width = "100%" class = "lazy lazy-fadeIn"></p>
                           <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit, 
                              sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. 
                              Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris 
                              nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in 
                              reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla 
                              pariatur.</p>
                           
                           <p> <img data-src = "/framework7/images/pic8.jpg" 
                              width = "100%" class = "lazy lazy-fadeIn"></p>
                              
                           <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. 
                              Praesent laoreet nisl eget neque blandit lobortis. Sed sagittis risus 
                              id vestibulum finibus. Cras vestibulum sem et massa hendrerit maximus. 
                              Vestibulum suscipit tristique iaculis. Nam vitae risus non eros auctor 
                              tincidunt quis vel nulla. Sed volutpat, libero ac blandit vehicula, est 
                              sem gravida lectus, sed imperdiet sapien risus ut neque.</p>
                           
                           <p><b>Using as background image:</b></p>
                           
                           <div data-background = "/framework7/images/pic7.jpg" 
                              style = "background: #aaa; height:60vw; background-size-cover" 
                              class = "lazy lazy-fadeIn">
                           </div>
                           
                           <p>Sed ut perspiciatis unde omnis iste natus error sit voluptatem 
                              accusantium doloremque laudantium, totam rem aperiam, eaque ipsa quae ab 
                              illo inventore veritatis et quasi architecto beatae vitae dicta sunt explicabo. 
                              Nemo enim ipsam voluptatem quia voluptas sit aspernatur aut odit aut fugit, 
                              sed quia consequuntur magni dolores eos qui ratione voluptatem sequi 
                              nesciunt.</p>
                        </div>
                     </div>
                  </div>
                  
               </div>
            </div>
         </div>
      </div>
      
      <script type = "text/javascript" 
         src = "https://cdnjs.cloudflare.com/ajax/libs/framework7/1.4.2/js/framework7.min.js"></script>
      
      <script>var myApp = new Framework7();</script>
   </body>

</html>

輸出

讓我們執行以下步驟來檢視上面給出的程式碼是如何工作的：

將上面給出的 HTML 程式碼儲存為framework7_lazy_load.html檔案到您的伺服器根目錄。
開啟此 HTML 檔案，地址為https:///framework7_lazy_load.html，顯示的輸出如下所示。
此示例指定了影像的延遲載入，當您向下滾動時，影像將載入到頁面上。

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