Reactive Forms & Validation Flashcards
7 cards from real Angular Web Framework practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Reactive Forms & Validation flashcards as text
Which method on a FormGroup marks all descendant controls as touched?
Answer: markAllAsTouched()
`markAllAsTouched()` recursively marks every control in the group and its children as touched.
What does the `updateOn` option set to `'blur'` do in a reactive form control?
Answer: Triggers validation only when the field loses focus
Setting `updateOn: 'blur'` defers value and validity updates until the user leaves the field.
Which validator ensures a control's value matches a given regular expression?
Answer: Validators.pattern()
`Validators.pattern()` accepts a string or RegExp and validates the control value against it.
How do you disable a specific FormControl inside a FormGroup without removing it?
Answer: Both A and C are valid approaches
You can call `control.disable()` at runtime or pass `{ disabled: true }` as the initial state object to `FormBuilder.control()`.
What value does `formControl.value` return when the control is disabled?
Answer: The current value is still returned
A disabled control retains its value; `formControl.value` still returns the current value even when disabled.
Which FormGroup method returns the raw value including disabled controls?
Answer: getRawValue()
`FormGroup.getRawValue()` returns the values of all controls including those that are disabled.
What is the purpose of `AbstractControl.setErrors()` in reactive forms?
Answer: Manually set validation errors on a control bypassing validators
`setErrors()` lets you programmatically assign an error map to a control, useful for server-side validation results.