listenToOnce
优质
小牛编辑
137浏览
2023-12-01
描述 (Description)
它与listenTo事件相同,但导致listento仅在删除回调函数之前发生一次。
语法 (Syntax)
object.listenToOnce(other, event, callback)
参数 (Parameters)
other - 它定义另一个对象的名称。
event - 它绑定一个对象。
callback - 它是对代码的引用,并使用object作为上下文进行调用。
例子 (Example)
<!DOCTYPE html>
<html>
<head>
<title>Event Once Example</title>
<script src = "https://code.jquery.com/jquery-2.1.3.min.js"
type = "text/javascript"></script>
<script src =
"https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.8.2/underscore-min.js"
type = "text/javascript"></script>
<script src = "https://cdnjs.cloudflare.com/ajax/libs/backbone.js/1.1.2/backbone-min.js"
type = "text/javascript"></script>
</head>
<body>
<script type = "text/javascript">
//Create an object 'myVal' and 'myVal1' and extend them using Backbone.Events method
var myVal = _.extend({name:'Saurav Ganguly'}, Backbone.Events);
var myVal1 = _.extend({name:'Sachin Tendulkar'}, Backbone.Events);
//created the 'listenMe' callback function and invoked when one object listen to
//particular event on another object
var listenMe = function() {
document.write("The value is: ");
document.write(this.name);
};
//The object 'myVal1' listen once for the 'listenMe' event triggered on object 'myVal'
myVal1.listenToOnce(myVal, 'listenMe', listenMe);
//The 'myVal' has no listenMe event and display the value of 'myVal1'
myVal.trigger('listenMe');
</script>
</body>
</html>