Create web notification with timeout

How do I create a TypeScript web notification with a set timeout?

I created the following code but doesn't work in closing the notification before the default timeout:

export function createNotification(title: string, body: string) {
    let now: Date = new Date(Date.now());
    let date = now.add(5).seconds();

    let options = {
        body: body,
        requireInteraction: false,
        timestamp: date
    };
    new Notification(title, options);
}

As a test I want to create a notification in TypeScript which lasts five seconds, overriding the browsers default behaviour. I can't see any further options listed in the TypeScript typings file which would be helpful to me:

I'm using for developing and testing this software using Chrome, although I use Firefox as my main browser. So any solutions which works correctly in Chrome, but doesn't include hacks or browser specific code would be fine.

Did you try Notification.close() ?

function spawnNotification(theBody,theIcon,theTitle) {
  var options = {
      body: theBody,
      icon: theIcon
  }

  var n = new Notification(theTitle,options);
  setTimeout(n.close.bind(n), 4000);
}

source: https://developer.mozilla.org/en-US/docs/Web/API/Notification/close