Can all intervals set within NGZone be cleared?

Question

Can all intervals set within NGZone be cleared?

Within my Angular2 component, I have a custom 3rd party JQuery plugin that is initialized in the OnInit event. Unfortunately, this 3rd party library uses setIntervals extensively. This poses a problem when navigating away from the view as the intervals remain active and continue to trigger the widget behavior on other views.

The issue lies in the fact that the 3rd party component lacks a way to destroy or clear these intervals. My initial solution was to call destroy() in the Angular2 OnDestroy method.

To address this, I attempted to use Zone for cleanup purposes. Here's what I did:

constructor(elementRef: ElementRef, public zone: NgZone) {
    }

ngOnInit() {
    this.zone.runOutsideAngular(() => {
        $(this.elementRef).3rdPartyWidgetStart();
    });}

ngOnDestroy() {
    var componentzone=this.zone;
    //So do something here to clear intervals set within Zone???
}

My expectation was that this code would clear the intervals upon navigation away. However, this didn't turn out to be the case. I also tried using run instead of runOutsideAngular, but it didn't solve the issue. I then explored the possibility of Zone keeping track of all intervals set and attempting to clear them through that. While Zone does seem to keep track of the intervals, accessing and clearing them proved challenging. Any suggestions using Angular 2 RC - or if I'm approaching this incorrectly with Zones, please advise. As this concept is new to me.

javascript typescript angular zone

Answer 1

Answer №1

It is important to note that utilizing Zone directly carries some level of risk:

    Zone.current.fork({
        name: 'jquery', onScheduleTask: (parentZoneDelegate: ZoneDelegate, currentZone: Zone, targetZone: Zone,
                                                  task: Task)=>
        {
            if(task.source === 'setInterval'){
                console.log('capture', task);
                //data has handleId property, interval id
                this.interval = task.data; 
            }
            return parentZoneDelegate.scheduleTask(targetZone, task);
        }
    }).run(()=>
    {
        setInterval(()=>
        {
            console.log('jquery interval', Zone.current);
        }, 5000);
    });

In a different part of the codebase:

clearInterval(this.interval.handleId);

This implementation may require additional checks and thorough documentation review. Additionally, it's advisable to verify compatibility with Angular.

Answer 2

It is important to note that utilizing Zone directly carries some level of risk:

    Zone.current.fork({
        name: 'jquery', onScheduleTask: (parentZoneDelegate: ZoneDelegate, currentZone: Zone, targetZone: Zone,
                                                  task: Task)=>
        {
            if(task.source === 'setInterval'){
                console.log('capture', task);
                //data has handleId property, interval id
                this.interval = task.data; 
            }
            return parentZoneDelegate.scheduleTask(targetZone, task);
        }
    }).run(()=>
    {
        setInterval(()=>
        {
            console.log('jquery interval', Zone.current);
        }, 5000);
    });

In a different part of the codebase:

clearInterval(this.interval.handleId);

This implementation may require additional checks and thorough documentation review. Additionally, it's advisable to verify compatibility with Angular.

Answer 3

Answer №2

1) run versus runOutsideAngular

When you use runOutsideAngular, the change detection will not be triggered after asynchronous operations (setTimeout, events, XHR, etc.) initiated from your plugin.

On the other hand, when using run (or even better, calling 3rdPartyWidgetStart directly), the change detection will execute after any asynchronous operation.

Choose the method that best fits your project needs (e.g., do you need to run the change detection after setTimeout, events, etc.).

2) Cleaning up setTimeouts

One option is to create a new zone with a ZoneDelegate that keeps track of timer ids and cancels them in the ngOnDestroy method.

However, the most effective solution would likely involve fixing the jQuery plugin itself.

Answer 4

1) run versus runOutsideAngular

When you use runOutsideAngular, the change detection will not be triggered after asynchronous operations (setTimeout, events, XHR, etc.) initiated from your plugin.

On the other hand, when using run (or even better, calling 3rdPartyWidgetStart directly), the change detection will execute after any asynchronous operation.

Choose the method that best fits your project needs (e.g., do you need to run the change detection after setTimeout, events, etc.).

2) Cleaning up setTimeouts

One option is to create a new zone with a ZoneDelegate that keeps track of timer ids and cancels them in the ngOnDestroy method.

However, the most effective solution would likely involve fixing the jQuery plugin itself.

Can all intervals set within NGZone be cleared?

Answer №1

Answer №2

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