For Angular 5

app.module.ts

import {DatePipe} from '@angular/common';
.
.
.
providers: [DatePipe]

demo.component.ts

import { DatePipe } from '@angular/common';
.
.
constructor(private datePipe: DatePipe) {}

ngOnInit() {
   var date = new Date();
   console.log(this.datePipe.transform(date,"yyyy-MM-dd")); //output : 2018-02-13
}

more information angular/datePipe

Example as per doc

@Component({
  selector: 'date-pipe',
  template: `<div>
    <p>Today is {{today | date}}</p>
    <p>Or if you prefer, {{today | date:'fullDate'}}</p>
    <p>The time is {{today | date:'jmZ'}}</p>
  </div>`
})
export class DatePipeComponent {
  today: number = Date.now();
}

Template

{{ dateObj | date }}               // output is 'Jun 15, 2015'
{{ dateObj | date:'medium' }}      // output is 'Jun 15, 2015, 9:43:11 PM'
{{ dateObj | date:'shortTime' }}   // output is '9:43 PM'
{{ dateObj | date:'mmss' }}        // output is '43:11'
{{dateObj  | date: 'dd/MM/yyyy'}} // 15/06/2015

To Use in your component.

@Injectable()
import { DatePipe } from '@angular/common';
class MyService {

  constructor(private datePipe: DatePipe) {}

  transformDate(date) {
    this.datePipe.transform(myDate, 'yyyy-MM-dd'); //whatever format you need. 
  }
}

In your app.module.ts

providers: [DatePipe,...] 

all you have to do is use this service now.

Try this below code it is also works well in angular 2

<span>{{current_date | date: 'yyyy-MM-dd'}}</span>