Ext.js 自定义事件
事件是当类发生某些事情时被触发的东西。例如，当一个按钮被点击或在元素呈现之前/之后。
编写事件的方法
使用侦听器的内置事件
稍后附加事件
自定义事件
使用监听器的内置事件
Ext JS 提供用于在 Ext JS 文件中编写事件和自定义事件的监听器属性。
在 Ext JS 中编写监听器
我们将在前面的程序中通过向面板添加一个监听属性来添加监听器。
<!DOCTYPE html>
<html>
<head>
<link href = "https://cdnjs.cloudflare.com/ajax/libs/extjs/6.0.0/classic/theme-neptune/resources/theme-neptune-all.css"
rel = "stylesheet" />
<script type = "text/javascript"
src = "https://cdnjs.cloudflare.com/ajax/libs/extjs/6.0.0/ext-all.js"></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>
上述程序将产生以下结果-
这样我们也可以在 listeners 属性中编写多个事件。
同一个监听器中的多个事件
<!DOCTYPE html>
<html>
<head>
<link href = "https://cdnjs.cloudflare.com/ajax/libs/extjs/6.0.0/classic/theme-neptune/resources/theme-neptune-all.css"
rel = "stylesheet" />
<script type = "text/javascript"
src = "https://cdnjs.cloudflare.com/ajax/libs/extjs/6.0.0/ext-all.js"></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>
稍后附加事件
在前面写事件的方法中，我们在创建元素的时候在监听器中写了事件。另一种方式是附加事件。
<!DOCTYPE html>
<html>
<head>
<link href = "https://cdnjs.cloudflare.com/ajax/libs/extjs/6.0.0/classic/theme-neptune/resources/theme-neptune-all.css"
rel = "stylesheet" />
<script type = "text/javascript"
src = "https://cdnjs.cloudflare.com/ajax/libs/extjs/6.0.0/ext-all.js"></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>
上述程序将产生以下结果-
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。以下示例说明了如何编写自定义事件。
<!DOCTYPE html>
<html>
<head>
<link href = "https://cdnjs.cloudflare.com/ajax/libs/extjs/6.0.0/classic/theme-neptune/resources/theme-neptune-all.css"
rel = "stylesheet" />
<script type = "text/javascript"
src = "https://cdnjs.cloudflare.com/ajax/libs/extjs/6.0.0/ext-all.js"></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>
页面加载完毕且文档准备就绪后，将出现带有按钮的 UI 页面，当我们在 5 秒后触发事件时，文档就准备好了。 5 秒后会出现警告框。
在这里，我们编写了自定义事件 'myEvent' 并且我们将触发事件作为 button.fireEvent(eventName);
