javascript - Angular 2 - Component property changes but view does not update -

i'm attempting learn angular 2. understanding interpolated items in view update when corresponding variable updated in model, in code below not see behavior.

import { component, oninit } '@angular/core';    @component({      selector: 'ai-header',      templateurl: 'app/header/header.component.html',      styleurls: ['app/header/header.component.css'],  })    export class headercomponent implements oninit {      currenttime: date = new date();        getcurrenttime(): void{          let datetime = new date();          let year = datetime.getfullyear();          let month = datetime.getmonth();          let day = datetime.getdate();          let hour = datetime.gethours();          let minute = datetime.getminutes();          let second = datetime.getseconds();          datetime = new date(year, month, day, hour, minute, second)                    this.currenttime = datetime;      }        ngoninit(): void {          setinterval(this.getcurrenttime, 1000);      }     }

why view not updating when 'currenttime' property of component updated?

i think should be:

ngoninit(): void {     setinterval(this.getcurrenttime.bind(this), 1000); }