$watch in Typescript

Question

I need that after I start the application it runs a set of functions every 20 seconds or each time q a json is updated,in angular 1 had the $watch that could be used for such functionality,in angular 2 I do not know if it has something similar,I tried with a while,

Answer 1

You can use the javascript’s native setInterval function to run something indefinitely, for a period of time .

But each time a JSON is changed it suggests me access to the file system, which you don’t have access to from the browser. Perhaps the service you use should send a notification, to indicate that there has been a change. I believe that any solution that does this kind of monitoring either uses the time for verification or receives a notification. I took a look at the $watch specification and it does something like this (time x notification).

See example of setInterval usage:

@Component()
export class MeuComponent implements OnDestroy, AfterViewInit
{
    private tokenInterval: any;

    ngAfterViewInit()
    {
       let tempoSeg = 1;
       this.tokenInterval = setInterval(()=> this.minhaF(), tempoSeg * 1000);

    }

    ngOnDestroy()
    {
       if (!!this.tokenInterval) clearInterval(this.tokenInterval);
    }

    private minhaF()
    {

       console.log('minhaF executada');

    }




}