Angular 8 Reactive Form input değerini güncellemek.

form.component.ts

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

@Component({
  selector: 'app-form',
  templateUrl: './form.component.html',
  styleUrls: ['./form.component.scss']
})

export class FormComponent implements OnInit {
  updateForm: FormGroup;  
  constructor(private formBuilder: FormBuilder) { }  
  ngOnInit() {
    this.updateForm = this.formBuilder.group({
      title: ['', [Validators.required, Validators.required]],
      slug: ['', [Validators.required, Validators.required]],
      description: ['', [Validators.required, Validators.required]]
    });
  }  
  
  onBlurTitle() {
    const slug = 'bu-bir-slug-olmali';
    this.updateForm.patchValue({ slug: slug });
  }
  
}