Angular / Typescript - 无法更新订阅中的外部变量 function

Question

below is my code, I just want to query the backend if email already registered or not, however, no matter what email I pass to the verifyEmail function, the "registered" variable always false, how can I update the registered variable according to the backend response? Thanks

export class MyClass {

   registered: boolean = false;
   message: string = ''

   verifyEmail(email) { 
        this.registered= false
        
        let verifyEmailUrl = "/backend/GetUserByEmail";
        this.http.post(verifyEmailUrl, {
            email: email
        }).subscribe(
            (data) => {
                if (data["user"]) { // can find a user
                    this.message = 'This email has already been registered'
                    this.registered= true
                }
            });
}

Answer 1

You are using an arrow function, your scope should be shared and this.registered should be updated appropriately. Please provide a console.log of data or more relevant code. The issue does not appear to be identifiable from your question.

Answer 2

How do you check registered value? You can't get this value immediately after verifyEmail execution, because value will update some time later. You can create BehaviorSubject then subscribe on it and get register value anywhere when it will update

export class MyClass {

   registered$ = new BehaviorSubject<boolean>();
   message: string = ''

   verifyEmail(email) {             
        let verifyEmailUrl = "/backend/GetUserByEmail";
        this.http.post(verifyEmailUrl, {
            email: email
        }).subscribe(
            (data) => {
                if (data["user"]) { // can find a user
                    this.message = 'This email has already been registered'
                    this.registered$.next(true)
                } else {
                    this.registered$.next(false)
                }

            });
}

In outer code:

myClassObject.registered$.asObservable().subscribe(registered => console.log(registered));