Javascript类返回未定义 [英] Javascript Class returns undefined

问题描述

使用此代码时，该函数返回未定义而不是对象。

When using this Code the function returns undefined instead of an object.

function Oauth_User_Profile() {
    this.username = "=";
    this.password = "=";
    this.refresh_token = "=";
    this.access_token = "=";
    this.request = function(url, formData, method, then) {
        var xhttp = new XMLHttpRequest();
        xhttp.onreadystatechange = function() {
            if(xhttp.readyState == 4 && xhttp.status == 200)
            {
                var j = JSON.parse(this.responseText);
                then(j);
            }
        }
        xhttp.open(method, url); 
        xhttp.send(JSON.stringify(formData)); 
    }
}

var oauth_user_profile = Oauth_User_Profile();
oauth_user_profile.username = "sample";

其他班级的代码差不多，但效果很好，所以我没有知道为什么它不能正常运行

I've got nearly the same Code for other classes which is working fine, so I don't know why this isn't running properly

重复：
问题被标记为[如何从异步调用返回响应？。但是，我不想返回调用结果，我想返回一个包含用户名，密码，refresh_token ...和可以运行的方法的对象。删除异步部分时，我遇到了完全相同的问题：

Duplicate: Question was marked as a duplicate for [How do I return the response from an asynchronous call?. However, I don't want to return the result of the call, I want to return an object which contains username, password, refresh_token... AND a method which can be run. I run into the exact same problem when removing the async-part:

function Oauth_User_Profile() {
 this.username = "=";
 this.password = "=";
 this.refresh_token = "=";
 this.access_token = "=";
}

这仍然会产生错误：未捕获的TypeError：无法设置属性'未定义
的用户名，位于testm.html：67

推荐答案

您丢失了 new 关键字：

var oauth_user_profile = new Oauth_User_Profile();

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