Displaying the current data and time

So I am trying to display the current data and time, but did does not change it will display 12:30 , but if few mins pass it well not change it will 12:30.
how can I make it so the time display correctly?

    this.datatime = new Date();
<h2>{{datatime | date:'h:mm'}}</h2>
 <h4>{{datatime | date:'EEEE MMMM dd yyyy'}}</h4>
setInterval(() => {  
  this.datatime = new Date();
}, 1000);

Yes That what I want thank you very much