对于对象变量,我不了解JavaScript范围。我定义了以下类:
class DataHandler {
constructor(boardIDA, boardIDB, accessToken, eventA, eventB) {
this.times = [];
this.eventA = eventA;
this.eventB = eventB;
this.apiURLA = "https://api.particle.io/v1/devices/" + boardIDA + "/events/" + eventA + "/?access_token=" +
accessToken;
this.apiURLB = "https://api.particle.io/v1/devices/" + boardIDB + "/events/" + eventB + "/?access_token=" + accessToken;
this.eventListenerA = new EventSource(this.apiURLA);
this.eventListenerB = new EventSource(this.apiURLB);
this.addListener(this.eventListenerA,
eventA);
this.addListener(this.eventListenerB, eventB);
}
addListener(eventSrc, eventName) {
eventSrc.addEventListener(eventName, function(info) {
alert(eventName);
var parsedData = JSON.parse(info.data);
this.times.push(parsedData);
});
}
}
问题出在哪里this.times
。我已经在构造函数中声明了它。不过,我似乎无法访问它addListener
-我得到一个错误,说我想叫push
上undefined
。我究竟做错了什么?
您没有在其中访问它addListener
,而是在匿名事件处理程序中尝试访问它,该事件使用来调用this
。
addListener(eventSrc, eventName) {
var handler = function(info) {
alert(eventName);
var parsedData = JSON.parse(info.data);
this.times.push(parsedData);
};
eventSrc.addEventListener(eventName, handler.bind(this));
}
本文收集自互联网,转载请注明来源。
如有侵权,请联系 [email protected] 删除。
我来说两句