How to set null for date form field in reactive form in angular 6

Question

How to set null for date filed in reactive form.I tried but not working.Anyone know please help to find the solution.

app.component.html:

<input type="text" class="form-control" formControlName="publishdate" ngbDatepicker #datepicker="ngbDatepicker">

app.component.ts:

this.registerForm = this.fb.group({}); 
this.registerForm.addControl('publishdate', new FormControl('', null));

Answer 1

Change your input be like

<input type="text" class="form-control" formControlName="publishdate" ngbDatepicker #d="ngbDatepicker">

And so, the HTML should be like,

<form class="form-inline" [formGroup]="registerForm">
 <div class="form-group">
   <div class="input-group">
     <input type="text" class="form-control" formControlName="publishdate" ngbDatepicker #d="ngbDatepicker">
     <div class="input-group-append">
       <button class="btn btn-outline-secondary calendar" (click)="d.toggle()" type="button">
       </button>
     </div>
    </div>
   </div>
 </form>

And TS,

import {Component, OnInit} from '@angular/core';
import { FormControl, FormGroup, FormBuilder, ValidationErrors } from "@angular/forms";

@Component({
  selector: 'ngbd-datepicker-popup',
  templateUrl: './datepicker-popup.html'
})
export class NgbdDatepickerPopup implements OnInit {

  registerForm: FormGroup;

  constructor(private fb: FormBuilder){}

  ngOnInit(){
    this.registerForm = this.fb.group({});
    this.registerForm.addControl('publishdate', new FormControl('', null));
  }
}

Working Example: https://stackblitz.com/edit/ngb-datepicker-validation-opt-out-vk6maq