Ext.js 自定义事件和监听器

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事件是在类发生的时候触发的。例如，当一个按钮被点击或元素被渲染之前/之后。

写事件的方法:

内置事件使用侦听器
附加事件监听
自定义事件

内置事件使用侦听器

Ext JS提供了用于在Ext JS文件中编写事件和自定义事件的侦听器属性。

在Ext JS中编写侦听器

我们将通过在面板中添加listen属性来将监听器添加到上一个程序中，如下所示:

<!DOCTYPE html>
<html>
   <head>
      <link href="https://cdn.bootcss.com/extjs/6.0.0/classic/theme-neptune/resources/theme-neptune-all.css" rel="external nofollow" target="_blank"  rel="external nofollow" target="_blank"  rel="external nofollow" target="_blank"  rel="external nofollow" target="_blank"  rel="stylesheet" />
      <script type="text/javascript" src="https://cdn.bootcss.com/extjs/6.0.0/ext-all.js" rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow" ></script>
      <script type="text/javascript">
         Ext.onReady(function(){
            Ext.create('Ext.Button', {
               renderTo: Ext.getElementById('helloWorldPanel'),
               text: 'My Button',
               listeners: {
                  click: function() {
                     Ext.MessageBox.alert('Alert box', 'Button is clicked');	
                  }
               }
            });
         });
      </script> 
   </head>
   <body>
      <p> Please click the button to see event listener </p>
      <div id = 'helloWorldPanel' />   <!--  panel will be rendered here-- >
   </body>
</html>

这会产生以下结果:

这样我们可以在listeners属性中写多个事件。

同一个侦听器中的多个事件

<!DOCTYPE html>
<html>
   <head>
      <link href="https://cdn.bootcss.com/extjs/6.0.0/classic/theme-neptune/resources/theme-neptune-all.css" rel="external nofollow" target="_blank"  rel="external nofollow" target="_blank"  rel="external nofollow" target="_blank"  rel="external nofollow" target="_blank"  rel="stylesheet" />
      <script type="text/javascript" src="https://cdn.bootcss.com/extjs/6.0.0/ext-all.js" rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow" ></script>
      <script type="text/javascript">
         Ext.onReady(function(){
            Ext.get('tag2').hide()
            Ext.create('Ext.Button', {
               renderTo: Ext.getElementById('helloWorldPanel'),
               text: 'My Button',
               listeners: {
                  click: function() {
                     this.hide();
                  },
                  hide: function() {
                     Ext.get('tag1').hide();
                     Ext.get('tag2').show();
                  }
               }
            });
         });           
      </script> 
   </head>
   <body>
   <div id = "tag1">Please click the button to see event listener.</div>
   <div id = "tag2">The button was clicked and now it is hidden.</div>
   <div id = 'helloWorldPanel' />   <!--  panel will be rendered here-- >
   </body>
</html>

运行效果如下：

附加事件监听

在前面的写事件的方法中，我们在创建元素时在侦听器中写入事件。

也可以在之后的代码中使用附加事件监听的方式:

<!DOCTYPE html>
<html>
   <head>
      <link href="https://cdn.bootcss.com/extjs/6.0.0/classic/theme-neptune/resources/theme-neptune-all.css" rel="external nofollow" target="_blank"  rel="external nofollow" target="_blank"  rel="external nofollow" target="_blank"  rel="external nofollow" target="_blank"  rel="stylesheet" />
      <script type="text/javascript" src="https://cdn.bootcss.com/extjs/6.0.0/ext-all.js" rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow" ></script>
      <script type="text/javascript">
         Ext.onReady(function(){
            var button = Ext.create('Ext.Button', {
               renderTo: Ext.getElementById('helloWorldPanel'),
            text: 'My Button'
            });

            // This way we can attach event to the button after the button is created.
            button.on('click', function() {
               Ext.MessageBox.alert('Alert box', 'Button is clicked');
            });
         });
      </script> 
   </head>
   <body>
      <p> Please click the button to see event listener </p>
      <div id = 'helloWorldPanel' />   <!--  panel will be rendered here-- >
   </body>
</html>

运行结果如下：

自定义事件

我们可以在ext JS中编写自定义事件，并使用fireEvent方法触发事件，下面的示例解释了如何编写自定义事件。

<!DOCTYPE html>
<html>
   <head>
      <link href="https://cdn.bootcss.com/extjs/6.0.0/classic/theme-neptune/resources/theme-neptune-all.css" rel="external nofollow" target="_blank"  rel="external nofollow" target="_blank"  rel="external nofollow" target="_blank"  rel="external nofollow" target="_blank"  rel="stylesheet" />
      <script type="text/javascript" src="https://cdn.bootcss.com/extjs/6.0.0/ext-all.js" rel="external nofollow"  rel="external nofollow"  rel="external nofollow"  rel="external nofollow" ></script>
      <script type="text/javascript">
         Ext.onReady(function(){
            var button = Ext.create('Ext.Button', {
               renderTo: Ext.getElementById('helloWorldPanel'),
               text: 'My Button',
               listeners: {
                  myEvent: function(button) {
                     Ext.MessageBox.alert('Alert box', 'My custom event is called');
                  }
               }
            });
            Ext.defer(function() {
               button.fireEvent('myEvent');
            }, 5000);
         }); 
      </script> 
   </head>
   <body>
      <p> The event will be called after 5 seconds when the page is loaded. </p>
      <div id = 'helloWorldPanel' />   <!--  panel will be rendered here-- >
   </body>
</html>

运行结果如下（为了节省展示时间，图中效果使用2秒的定时器）：

一旦页面被加载并且文档准备就绪，UI页面与按钮将出现，并且我们在5秒后触发事件文档准备就绪，警报框将在5秒后出现。

这里我们写了自定义事件\'myEvent\'，我们将事件触发为button.fireEvent（eventName）