Managing properties of classes within callbacks using TypeScript

I am currently working on the following task:

class User {

    name: string;

    userService: UserService; //service responsible for fetching data from server

    successCallback(response: any) {
          this.name = string; 
    }

    setUser() {     
       var xhr: JQueryXHR = this.userService.fetchUser(); //Returns JQueryXHR object
       xhr.then(this.successCallback);
    }
}

When I invoke the setUser method on an instance of the User class:

var user: User = new User();
user.setUser(); 

The issue is that this.name in successCallback is returning undefined.

Is there a way to reference the attribute of the class within the callback function?

Answer №1

The reason for this behavior is that the function is being assessed within the context of window.

To resolve this issue, enclose the xhr.then method call:

xhr.then(response => {
    this.successCallback(response);
});

Using the => arrow function ensures that this points to the current instance of the class.

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