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

Output

https://undefined:undefined@mnyurl.de/undefined/vplan/vdaten/VplanKl20200317.xml // undefined
https://www.myurl.de/10192417/vplan/vdaten/VplanKl20200317.xml // What it should be

如您所见，我正在尝试请求一个 xml 文件。 我发现 this.username 等是未定义的。 我该如何解决？ 这是什么原因？ （对不起，我是 Javascript 新手）

Answer 1

在 javascript 构造函数被称为构造函数，而不是 class 的名称，所以你的 function ScheduleDownloader 永远不会被调用。 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

这不是你在 es6 中声明构造函数的方式。 尝试这个

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

Answer 3

您的class定义设置不正确。 我认为您的意思是使用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