Execute a function in Angular2 every 10 seconds

Question

Execute a function in Angular2 every 10 seconds

I've been working on a project that requires a Timer to make an API call every 10 seconds. I tried using setTimeout, but encountered an issue where it turned into an infinite loop. Even when navigating to another page, it continued to execute the if condition.

Here's an example of how I'm currently implementing the Timer:

In a method, I use the following code to initiate the 10-second API calls:

setTimeout(() => {
    this.onTimeOut();
}, 1000);

This is the onTimeOut() method:

onTimeOut() {
    this.ApiCall().then(
    success => {
    if(success ['ok'] == 0){
        this.navCtrl.push(myPage);
    }
    },
    error => { console.log(error); });
}
setTimeout(() => {
    this.onTimeOut();
}, 1000);
}

I've heard about Debounce and rxjs/rs, but I'm unfamiliar with them. Can you provide some advice on how to achieve the same result using those methods? Alternatively, if the current approach is more efficient, please explain why it turns into a loop.

The objective is to stop the timer once it enters the if condition and pushes the page.

angular typescript ionic-framework ionic2

Answer 1

Answer №1

It's recommended to utilize observables for better functionality

this.sub = Observable.interval(10000)
    .subscribe((val) => { console.log('called'); });

If you need to stop it, simply call

this.sub.unsubscribe();

Ensure to have interval imported by including

import 'rxjs/add/observable/interval';

Answer 2

It's recommended to utilize observables for better functionality

this.sub = Observable.interval(10000)
    .subscribe((val) => { console.log('called'); });

If you need to stop it, simply call

this.sub.unsubscribe();

Ensure to have interval imported by including

import 'rxjs/add/observable/interval';

Answer 3

Answer №2

Starting from RxJS version 6 and above, you can simply utilize the interval function.

import { interval } from 'rxjs';

// Perform a task after 10 seconds
interval(10000).subscribe(x => {
    this.executeTask();
});

You have the option to use Subscription along with the interval function.

import { interval, Subscription} from 'rxjs';
export class IntervalExample{
    mySubscription: Subscription

    constructor(){
        this.mySubscription = interval(5000).subscribe((x =>{
            this.performAction();
        }));
    }
    
    performAction(){
        // Action execution with unsubscribe to run only once
        this.mySubscription.unsubscribe();
    }
}

Answer 4

Starting from RxJS version 6 and above, you can simply utilize the interval function.

import { interval } from 'rxjs';

// Perform a task after 10 seconds
interval(10000).subscribe(x => {
    this.executeTask();
});

You have the option to use Subscription along with the interval function.

import { interval, Subscription} from 'rxjs';
export class IntervalExample{
    mySubscription: Subscription

    constructor(){
        this.mySubscription = interval(5000).subscribe((x =>{
            this.performAction();
        }));
    }
    
    performAction(){
        // Action execution with unsubscribe to run only once
        this.mySubscription.unsubscribe();
    }
}

Answer 5

Answer №3

Instead of relying on setTimeout in your Angular application, consider using Observables as a more effective solution. Observable offers a method called timer that can be implemented like this:

timer = Observable.timer(initialDelay, period);

timer.subscribe(tick => {
   // Your API call will be executed at regular intervals
});

I recommend leveraging RxJS and Observable for handling requests, rather than promises. This approach aligns better with the Angular methodology and RxJS is a highly versatile library.

Check out the RxJS Observable documentation

Answer 6

Instead of relying on setTimeout in your Angular application, consider using Observables as a more effective solution. Observable offers a method called timer that can be implemented like this:

timer = Observable.timer(initialDelay, period);

timer.subscribe(tick => {
   // Your API call will be executed at regular intervals
});

I recommend leveraging RxJS and Observable for handling requests, rather than promises. This approach aligns better with the Angular methodology and RxJS is a highly versatile library.

Check out the RxJS Observable documentation

Answer 7

Answer №4

To achieve your goal in Angular, utilize the observable.timer method.

 export class CurrentRunsComponent implements OnInit, OnDestroy {
  private timer;


  ngOnInit() {
    this.timer = Observable.timer(10000);
    this.timer.subscribe((t) => this.onTimeOut());
  }
   onTimeOut() {
    this.ApiCall().then(
    success => {
    if(success ['ok'] == 0){
        this.navCtrl.push(myPage);
    }
    },
    error => { console.log(error); });
}

   ngOnDestroy(){
    console.log("Destroy timer");

  }
}

Answer 8

To achieve your goal in Angular, utilize the observable.timer method.

 export class CurrentRunsComponent implements OnInit, OnDestroy {
  private timer;


  ngOnInit() {
    this.timer = Observable.timer(10000);
    this.timer.subscribe((t) => this.onTimeOut());
  }
   onTimeOut() {
    this.ApiCall().then(
    success => {
    if(success ['ok'] == 0){
        this.navCtrl.push(myPage);
    }
    },
    error => { console.log(error); });
}

   ngOnDestroy(){
    console.log("Destroy timer");

  }
}

Answer 9

Answer №5

While setTimeout itself is not the issue, the problem lies in your code. It appears you have created an infinite loop by not including a base condition in your recursive function.

To resolve this, make sure to add a base condition that will stop the recursion when navigating to other pages. This way, setTimeout will know when to cease calling onTimeOut() every second.

 private flag: boolean;

 ngOnInit() {
        this.flag = true;
 }

 ngOnDestroy() {
        this.flag = false;
 }
 onTimeOut() {
        this.ApiCall().then(
        success => {
        if(success ['ok'] == 0){
            this.navCtrl.push(myPage);
        }
        },
        error => { console.log(error); });
    }
     setTimeout(() => {
     if(this.flag){
        this.onTimeOut();
     }
    }, 1000);
    }

The ngOnDestroy method sets the flag to false, preventing the last call of the recursive function from entering the if block. As a result, each instance will return to its previous state and clear the stack recursively until it is completely emptied.

Answer 10

While setTimeout itself is not the issue, the problem lies in your code. It appears you have created an infinite loop by not including a base condition in your recursive function.

To resolve this, make sure to add a base condition that will stop the recursion when navigating to other pages. This way, setTimeout will know when to cease calling onTimeOut() every second.

 private flag: boolean;

 ngOnInit() {
        this.flag = true;
 }

 ngOnDestroy() {
        this.flag = false;
 }
 onTimeOut() {
        this.ApiCall().then(
        success => {
        if(success ['ok'] == 0){
            this.navCtrl.push(myPage);
        }
        },
        error => { console.log(error); });
    }
     setTimeout(() => {
     if(this.flag){
        this.onTimeOut();
     }
    }, 1000);
    }

The ngOnDestroy method sets the flag to false, preventing the last call of the recursive function from entering the if block. As a result, each instance will return to its previous state and clear the stack recursively until it is completely emptied.

Execute a function in Angular2 every 10 seconds

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

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