Strongly typed Angular form interfaces ~ http://azanebrain.github.io/news/angular-snafoo-testing-component-with-overriden-providers

angular-form-interface.ts

export interface MyFormValues {
    captcha: number;
    password: string;
    username: string;
}

export interface MyForm extends FormGroup {
    value: MyFormValues;
    controls: {
        captcha: AbstractControl;
        password: AbstracControl;
        username: AbstracControl;
    }
}

///

public myForm: MyForm

constructor(private formBuilder: FormBuilder) { }

ngOnInit() {
    this.myForm: MyForm = this.formBuilder.group({
        captcha: ['', Validators.required],
        usepasswordrname: ['', Validators.required],
        username: ['', Validators.required],
    })

    this.myForm.us // Now the 'username' property will be suggested

    this.myForm.value.fakeControl // This will generate an error to make sure you don't try and access  non-existent properties
}