Angular5- setInterval whiten the page - angular5

Question

I am adding notification to my project. The website should shown a number of notification numbers that the user have got without refreshing page. To do so i have used setInterval function inside ngOnInit but when i used it inside ngOnInit the page goes white and shows nothing but the timer is still running.
Here is how i have implement the code.
ngOnInit
ngOnInit() {
this.subscription = this.loginInfoService.getLoginChangeEmitter()
.subscribe(item => this.loginSuccess(item));
this.subscription = this.loginInfoService.getSiteNameEmitter()
.subscribe(item => this.getSiteName(item));
this.subscription = this.loginInfoService.getSiteDescriptionEmitter()
.subscribe(item => this.getSiteDescription(item));
if (innerWidth < 766) {
this.notificationBell = true;
} else {
this.notificationBell = false;
}
//if i add this line page goes white
setInterval(() => {
this.getAllNotification();
}, 3000);
}
Code to get all notification
getAllNotification() {
this.unSeenNotification = [];
this.notificationService.getAllNotifications().subscribe(
result => {
this.notificationModel = result;
this.showLoading = false;
result.forEach(result => {
if (!result.isSeen) {
this.unSeenNotification.push(result);
}
})
this.notificationCount = this.unSeenNotification.length;
},
error => {
this.alertService.error(error, "Error!");
});
}

Answer 1

You can below window interval:
export class FoobarComponent implements OnInit {
static intervalId: Number;
ngOnInit(): void {
this.startInterval();
}
startInterval() void {
if(FoobarComponent.intervalId) { // always undefined
window.clearInterval(this.intervalId);
}
FoobarComponent.intervalId = window.setInterval(() => {
console.log('Hi'); }, 1000);
}
}