title: FormControl disabled is not working with logic
body: <p>I want to make a field disabled from ts file.
  it is working fine when I <code>true/false</code> statically. but I want to make it logically. when my form in edit mode I will make the fields editable. when the form in view mode will disable the fields.</p>
  
  <blockquote>
    <p>It looks like you're using the disabled attribute with a reactive form
    directive. If you set disabled to true
          when you set up this control in your component class, the disabled attribute will actually be set in the DOM for
          you. We recommend using this approach to avoid 'changed after checked' errors.</p>
  
  <pre><code>  Example: 
    form = new FormGroup({
      first: new FormControl({value: 'Nancy', disabled: true}, Validators.required),
      last: new FormControl('Drew', Validators.required)
    });
  </code></pre>
  </blockquote>
  
  <p><strong>Logic when i change the mode</strong></p>
  
  <pre><code>editProspectDetails() {
      this.editProspectMode = !this.editProspectMode;
      this.isProspectDisabled();
  }
  </code></pre>
  
  <p><strong>FormControl Name:</strong></p>
  
  <pre><code>this.fb.group({
  prospect_pref_name: new FormControl({value: '', disabled: this.isProspectDisabled()}),
  })
  
  isProspectDisabled(){
      return true; // working
  
      but i want to make it conditionally
      console.log(this.editProspectMode); // it will return : true/ false
      return this.editProspectMode;
  }
  </code></pre>