Chapter quiz · Forms

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8 questions on Forms. Pass 70% to clear the chapter.

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Quiz

Forms — Chapter Quiz

Eight questions on template-driven vs reactive forms, validators, and typed forms.

0/ 9

Question 1
1
Which directive enables two-way template-driven binding to an input?
AformControlBformControlNameCngModelDngBind
[(ngModel)]="x" is the template-driven two-way binding. It lives in FormsModule. formControl and formControlName belong to reactive forms.
Question 2
2
Which class represents a single form field in reactive forms?
AFormGroupBFormControlCFormArrayDFormBuilder
FormControl is one input. FormGroup is an object of controls; FormArray is a list of controls; FormBuilder is a helper that constructs them.
Question 3
3
Where do validators go on a FormControl?
AA second argument to the constructorBA separate validators array passed to FormGroupCOnly on the template via attributesDInside the parent component decorator
new FormControl('', [Validators.required, Validators.minLength(3)]) — second arg accepts a single validator or an array.
Question 4
4
An async validator must return:
AA boolean immediatelyBA Promise or Observable of ValidationErrors | nullCA plain string error messageDA new FormControl
Async validators return Promise<ValidationErrors | null> or Observable<ValidationErrors | null> so Angular can wait on a remote check (uniqueness, etc.) before marking the control valid.
Question 5
5
Typed forms in Angular 14+ infer field types from:
AThe runtime valuesBThe structure passed to FormGroup/FormBuilderCA separate interface you pass to a Form decoratorDJSDoc comments
The shape of the object you pass to new FormGroup({...}) is inferred at the type level, giving form.value.email: string etc. without manual typing.
Question 6
6
A FormArray is used when the number of controls is dynamic at runtime.
TTrueFFalse
FormArray represents an ordered list of controls. Use it for repeatable rows: phone numbers, address blocks, line items.
Question 7
7
The built-in validator for a non-empty value is Validators.___.
Validators.required rejects empty strings, null, undefined, and (for checkboxes) false. There's also requiredTrue.
Question 8
8
Which modules / providers are commonly needed for reactive forms?
Select all that apply.
AReactiveFormsModuleBFormsModuleCprovideRouterDFormBuilder (injected service)EHttpClientModule
ReactiveFormsModule for the directives, FormBuilder as a helper. FormsModule is for template-driven forms; provideRouter and HttpClient are unrelated.