Exemple of ngb-date-parser-formatter implementation (ng-bootstrap)

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 {}

date.util.ts

import { NgbDateStruct } from "@ng-bootstrap/ng-bootstrap";

export static class DateUtil {
  public static ngbDateStructToDate(dateStruct : NgbDateStruct) : Date {
    if(!dateStruct) {
      return null;
    }
    return new Date(dateStruct.year, dateStruct.month - 1, dateStruct.day);
  }
}

ngb-date-fr-parser-formatter.ts

import { Injectable } from "@angular/core";
import { NgbDateParserFormatter, NgbDateStruct } from "@ng-bootstrap/ng-bootstrap";
import * as moment from "moment";
import {Parameters} from "../../app.parameter";
import {DateUtil} from "../../utils/date.util";

@Injectable()
export class NgbDateFRParserFormatter extends NgbDateParserFormatter {
    parse(value: string): NgbDateStruct {
    if (value && moment.isDate(value)) {
      const date = moment(value).toDate();
      return {
        year : date.getFullYear(),
        month : date.getMonth() + 1,
        day : date.getDate()
      };
    }
    return null;
  }

  format(date: NgbDateStruct): string {
    return date && moment(DateUtil.ngbDateStructToDate(date)).format(Parameters.defaultDisplayDatePattern);
  }
}