How Typescript allows variables to act as references to other variables

Imagine having a component with aliases for user data. This approach allows for shorter and cleaner variable names, making the code easier to read:

@Component({
    selector: 'my-view',
    templateUrl: './view.component.html',
    styleUrls: ['./view.component.scss']
})

export class ViewComponent implements OnInit {
    private plan: string;
    private status: string;
    private started: string;
    private cycle: string;

    constructor(private auth: Auth, private modal: Modal, private router: Router) {}

    ngOnInit(): void {
        this.plan = this.auth.userProfile.user_metadata.plan;
        this.status = this.auth.userProfile.user_metadata.token.status;
        this.started = this.auth.userProfile.user_metadata.token.epoch;
        this.cycle = this.auth.userProfile.user_metadata.cycle;

        if(this.plan === .... && this.cycle === ...) {

        }
    }
}

The convenience of these alias variables is compromised when user data updates. The values assigned during onInit do not automatically update, requiring a page refresh to reflect changes.

Is there a way to maintain the simplicity of alias variables like plan, status, started, cycle while ensuring they dynamically update based on the original data? Otherwise, readability may suffer from using longer variable names consistently.

Answer №1

When dealing with primitive values such as string, number, and boolean, they are always passed by value. Objects, on the other hand, are passed by reference. If you're looking for a way to achieve "pass by reference" behavior for primitive types, one approach is to wrap the values in an object and pass that object instead.

An alternative method is to use observables to inform other class instances of any changes in values, which can be a more effective approach.

For specific examples, you can refer to https://angular.io/docs/ts/latest/cookbook/component-communication.html#!#bidirectional-service

Answer №2

To achieve this, you have the option of utilizing either getter functions or ES6 properties:

@Component({
    selector: 'my-view',
    templateUrl: './view.component.html',
    styleUrls: ['./view.component.scss']
})
export class ViewComponent implements OnInit {
    constructor (private auth: Auth, private modal: Modal, private router: Router) {}

    private get subscriptionPlan(): string { // Using a property
        return this.auth.userProfile.user_metadata.subscription_plan;
    }

    private fetchStatus(): string { // Using a getter function
        return this.auth.userProfile.user_metadata.status;
    }

    ngOnInit(): void {
        if(this.subscriptionPlan === .... && this.fetchStatus() === ...) {

        }
    }
}

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