Cannot read property somevalue of undefined in Typescript Angular 5

Question

I am facing below issue when using the Angular 5 Services, Can you please help me what is wrong with the below code

I have gone through below questions but didn't help me

1. Question 1
2. Question 2
3. Question 3

I just want to initialize the value in the class and use it in the method

Though I have defined the url value in the class I'm getting error as Cannot read property 'url' of undefined for the line console.log(this.url);

@Injectable()
export class OwnService {

    public accessTokenvalue = '';
    public url = 'https://www.someurl.com/id=';
    constructor(private hp: HelpService) {
    }

    public gethpPhotos() {
        this.hp.login()
            .then(function (response: LoginResponse) {
                console.log(response);
                console.log(this.url);

            })
            .catch((error: any) => console.error(error));
    }
}

Answer 1

You just need to replace function (response: Response) with arrow function. Each function creates it's scope to which refers this inside it. Arrow function will preserve this.

.then((response: LoginResponse) => {
     console.log(response);
     console.log(this.url);
})