NodeJS this.var未定义

Question

index.js

const request = require('request');

class ScheduleDownloader {

ScheduleDownloader(schoolId, username, schoolPassword) {
    this.schoolId = schoolId;
    this.username = username;
    this.schoolPassword = schoolPassword;
}

getScheduleAtDate(dateString) {
    console.log(`https://${this.username}:${this.schoolPassword}@www.myurl.de/${this.schoolId}/vplan/vdaten/VplanKl${dateString}.xml`)
    /*request({url: `https://${this.username}:${this.schoolPassword}@www.myurl.de/${this.schoolId}/vplan/vdaten/VplanKl${dateString}.xml`}, (err, res, body) => {
        if(err) console.error(err);
        console.log(body);
    });*/    // COMMENTED OUT FOR TESTING
};

module.exports = ScheduleDownloader;


var s = new ScheduleDownloader(10192417, 'schueler', 'S53998t');
s.getScheduleAtDate(20200317); // For testing in this class

输出

https://undefined:[email protected]/undefined/vplan/vdaten/VplanKl20200317.xml // undefined
https://www.myurl.de/10192417/vplan/vdaten/VplanKl20200317.xml // What it should be

您可以看到我正在尝试请求xml文件。我发现this.username等是未定义的。我该如何解决？那是什么原因呢？ （对不起，我是Java语言的新手）

Answer 1

在javascript构造函数中称为构造函数，而不是类的名称，因此永远不会调用您的函数ScheduleDownloader。将其更改为构造函数：一些阅读：https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes

Answer 2

那不是在es6中声明构造函数的方式。试试这个

constructor(schoolId, username, schoolPassword) {
    this.schoolId = schoolId;
    this.username = username;
    this.schoolPassword = schoolPassword;
}

Answer 3

您的class定义未正确设置。我认为您打算使用constructor？

class ScheduleDownloader {

  constructor(schoolId, username, schoolPassword) {
      this.schoolId = schoolId;
      this.username = username;
      this.schoolPassword = schoolPassword;
  }

  getScheduleAtDate(dateString) {
      console.log(`https://${this.username}:${this.schoolPassword}@www.myurl.de/${this.schoolId}/vplan/vdaten/VplanKl${dateString}.xml`)
      /*request({url: `https://${this.username}:${this.schoolPassword}@www.myurl.de/${this.schoolId}/vplan/vdaten/VplanKl${dateString}.xml`}, (err, res, body) => {
          if(err) console.error(err);
          console.log(body);
      });*/    // COMMENTED OUT FOR TESTING
  };
}


var s = new ScheduleDownloader(10192417, 'schueler', 'S53998t');
s.getScheduleAtDate(20200317); // For testing in this class