angular2 ngbdatepicker how to format date in inputfield

"By default the datepicker comes with the basic implementation of this interface that just accepts dates in the ISO format. If you want to handle a different format (or multiple formats) you can provide your own implementation of the NgbDateParserFormatter and register it as a provider in your module." Source

In this GitHub gist you can find an example implementation. Here's a copy from that source:

app.component.ts

import { NgbDatepickerConfig, NgbDateParserFormatter } from '@ng-bootstrap/ng-bootstrap';
import { NgbDateFRParserFormatter } from "./ngb-date-fr-parser-formatter"

@Component({
    providers: [{provide: NgbDateParserFormatter, useClass: NgbDateFRParserFormatter}]
})
export class AppComponent {}

ngb-date-fr-parser-formatter.ts

import { Injectable } from "@angular/core";
import { NgbDateParserFormatter, NgbDateStruct } from "@ng-bootstrap/ng-bootstrap";

function padNumber(value: number) {
    if (isNumber(value)) {
        return `0${value}`.slice(-2);
    } else {
        return "";
    }
}

function isNumber(value: any): boolean {
    return !isNaN(toInteger(value));
}

function toInteger(value: any): number {
    return parseInt(`${value}`, 10);
}


@Injectable()
export class NgbDateFRParserFormatter extends NgbDateParserFormatter {
    parse(value: string): NgbDateStruct {
        if (value) {
            const dateParts = value.trim().split('/');
            if (dateParts.length === 1 && isNumber(dateParts[0])) {
                return {year: toInteger(dateParts[0]), month: null, day: null};
            } else if (dateParts.length === 2 && isNumber(dateParts[0]) && isNumber(dateParts[1])) {
                return {year: toInteger(dateParts[1]), month: toInteger(dateParts[0]), day: null};
            } else if (dateParts.length === 3 && isNumber(dateParts[0]) && isNumber(dateParts[1]) && isNumber(dateParts[2])) {
                return {year: toInteger(dateParts[2]), month: toInteger(dateParts[1]), day: toInteger(dateParts[0])};
            }
        }   
        return null;
    }

    format(date: NgbDateStruct): string {
        let stringDate: string = ""; 
        if(date) {
            stringDate += isNumber(date.day) ? padNumber(date.day) + "/" : "";
            stringDate += isNumber(date.month) ? padNumber(date.month) + "/" : "";
            stringDate += date.year;
        }
        return stringDate;
    }
}