Question

在对象变量方面，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);
    });
  }
}

问题在于this.times。我在构造函数中声明了它。但是，我似乎无法在addListener中访问它 - 我收到一条错误消息，说我试图在push上致电undefined。我做错了什么？

Answer 1

您没有在CV = c("a","b","c","d") AL = list(c(1,2),c(2,3,4),c(2)) CV[AL[[1]]] [1] "a" "b" sapply(CC,'[',AL)中访问它，您试图在匿名事件处理程序中访问它，该处理程序使用不同的addListener进行调用。

this

在类中访问构造函数属性

1 个答案: