有人可以告诉我为什么在下面的代码中使用 app.receivedEvent('deviceready')
而不是 this.receivedEvent('deviceready')
吗?
var app = {
// Application Constructor
initialize: function() {
this.bindEvents();
},
// Bind Event Listeners
//
// Bind any events that are required on startup. Common events are:
// 'load', 'deviceready', 'offline', and 'online'.
bindEvents: function() {
document.addEventListener('deviceready', this.onDeviceReady, false);
},
// deviceready Event Handler
//
// The scope of 'this' is the event. In order to call the 'receivedEvent'
// function, we must explicitly call 'app.receivedEvent(...);'
onDeviceReady: function() {
app.receivedEvent('deviceready');
},
// Update DOM on a Received Event
receivedEvent: function(id) {
var parentElement = document.getElementById(id);
var listeningElement = parentElement.querySelector('.listening');
var receivedElement = parentElement.querySelector('.received');
listeningElement.setAttribute('style', 'display:none;');
receivedElement.setAttribute('style', 'display:block;');
console.log('Received Event: ' + id);
}
};
最佳答案
这些注释实际上解释了使用 app
而不是 this
的原因:
// The scope of 'this' is the event. In order to call the 'receivedEvent'
// function, we must explicitly call 'app.receivedEvent(...);'
基本上,事件处理程序将使用其自己的 this
上下文调用事件回调(其中 this
将是事件对象)。
方法 receivedEvent
是在应用程序中定义的,而不是 this
(设置为事件回调函数内的事件对象)。在这种情况下,要调用 receivedEventil
,您可以将其作为包含对象 app
的方法来调用:
app.receivedEvent(...);
关于javascript - PhoneGap Index.js 文件为什么 app.receivedEvent 不是 this.receivedEvent,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/43501360/