如何在 Google AMP 中使用 amp-bind-macro 动态计算圆的面积？

借助 amp-bind-macro，可以创建一个 HTML 程序来动态计算圆的面积。给定输入后，页面会响应用户输入，在不刷新页面的情况下，根据提供的半径找到圆的区域并打印。

设置：要在我们的 AMP 页面中使用 amp-bind-macro，我们必须在文档头部导入 amp-bind 脚本。

例子：

HTML

  

    
    Foofle AMP amp-bind
  
    
  
    
  
    
    
  
    
    
    
  
    
        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
            }
        }
    
  
    
        
            body {
                -webkit-animation: none;
                -moz-animation: none;
                -ms-animation: none;
                animation: none
            }
        
    
  
    
        h1 {
            color: forestgreen;
            text-align: center;
        }
    

  

    
        Geeks For Geeks
    
      
    
    
        
  
            
                Enter the radius of the circle: 
            
            
            
              
            
                
                    The circle has an area of
                    0.
                
            
        
    

  

输出：