Identifying a specific value of a variable in Typescript

Question

Identifying a specific value of a variable in Typescript

I am currently developing an idle timeout feature for my application. Once the system detects inactivity, a modal window is triggered. Within this modal window, a timer is presented to the user. My goal is to have a way to determine when this timer reaches 0, so I can proceed with signing off the user accordingly.

export class IdleModalComponent implements OnInit {

counter$: Observable<number>;   
count = 300 // Here we set a countdown of 5 minutes before implementing the inactivity logic

constructor(public dialogRef: MatDialogRef<IdleModalComponent>) {
        this.counter$ = timer(0, 1000).pipe(
        take(this.count), 
        map(() => (--this.count)), 
    );
  }
}

By binding the counter observable in the HTML, the countdown is accurately displayed. The key requirement now is to identify:

this.count === 0.

angular typescript rxjs observable

Answer 1

Answer №1

To utilize the tap operator from RxJS library without the need for explicit subscription, you can implement it in the code snippet below:

this.counter$ = timer(0, 1000).pipe(
  take(this.count),
  map(() => (--this.count)),
  tap(val => {
    if (val === 0) {
      // Perform desired action like displaying a modal
      alert('The count is 0');
    }
  })
)

View Live Demo on StackBlitz

Answer 2

To utilize the tap operator from RxJS library without the need for explicit subscription, you can implement it in the code snippet below:

this.counter$ = timer(0, 1000).pipe(
  take(this.count),
  map(() => (--this.count)),
  tap(val => {
    if (val === 0) {
      // Perform desired action like displaying a modal
      alert('The count is 0');
    }
  })
)

View Live Demo on StackBlitz

Answer 3

Answer №2

A timer that emits numbers in sequence at a specified duration.

When using the map function, avoid causing any side effects and simply map the received value.

To observe the completion:

Subscribe to the observable
Include a complete callback function

const startingNumber = 10;

timer(0, 100)
  .pipe(
    take(startingNumber),
    map(value => startingNumber - value))
  .subscribe({
    next: result => console.log(result),
    complete: () => console.log('Process completed')
  });

Answer 4

A timer that emits numbers in sequence at a specified duration.

When using the map function, avoid causing any side effects and simply map the received value.

To observe the completion:

Subscribe to the observable
Include a complete callback function

const startingNumber = 10;

timer(0, 100)
  .pipe(
    take(startingNumber),
    map(value => startingNumber - value))
  .subscribe({
    next: result => console.log(result),
    complete: () => console.log('Process completed')
  });

Answer 5

Answer №3

Once the this.counter$ is finished executing.

this.counter$
  .subscribe(
    () => {}, // handling each count update
    () => {}, // error handling
    () => {
       // execution completed and `this.count === 0`
    }
  )

See Demo in Action

https://stackblitz.com/edit/rxjs-timer-complete?file=src/app/app.component.ts

Answer 6

Once the this.counter$ is finished executing.

this.counter$
  .subscribe(
    () => {}, // handling each count update
    () => {}, // error handling
    () => {
       // execution completed and `this.count === 0`
    }
  )

See Demo in Action

https://stackblitz.com/edit/rxjs-timer-complete?file=src/app/app.component.ts

Identifying a specific value of a variable in Typescript

Answer №1

Answer №2

Answer №3

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