@angular/forms

FormArray

Class

stable

Tracks the value and validity state of an array of FormControl, FormGroup or FormArray instances.

API

    
      class FormArray<TControl extends AbstractControl<any> = any> extends AbstractControl<
  override getError(errorCode: string, path?: string | (string | number)[] | undefined): any;  override hasError(errorCode: string, path?: string | (string | number)[] | undefined): boolean;  override readonly root: AbstractControl<any, any, any>;}

constructor

FormArray<TControl>

Creates a new FormArray instance.

@paramcontrolsTControl[]

An array of child controls. Each child control is given an index where it is registered.

@paramvalidatorOrOptsValidatorFn | AbstractControlOptions | ValidatorFn[] | null | undefined

A synchronous validator function, or an array of such functions, or an AbstractControlOptions object that contains validation functions and a validation trigger.

@paramasyncValidatorAsyncValidatorFn | AsyncValidatorFn[] | null | undefined

A single async validator or array of async validator functions

@returnsFormArray<TControl>

controls

ɵTypedOrUntyped<TControl, TControl[], AbstractControl<any, any, any>[]>

at

ɵTypedOrUntyped<TControl, TControl, AbstractControl<any, any, any>>

Get the AbstractControl at the given index in the array.

@paramindexnumber

Index in the array to retrieve the control. If index is negative, it will wrap around from the back, and if index is greatly negative (less than -length), the result is undefined. This behavior is the same as Array.at(index).

@returnsɵTypedOrUntyped<TControl, TControl, AbstractControl<any, any, any>>

push

void

Insert a new AbstractControl at the end of the array.

@paramcontrolTControl | TControl[]

Form control to be inserted

@paramoptions{ emitEvent?: boolean | undefined; }

Specifies whether this FormArray instance should emit events after a new control is added.

emitEvent: When true or not supplied (the default), both the statusChanges and valueChanges observables emit events with the latest status and value when the control is inserted. When false, no events are emitted.

NOTE: Pushing to the FormArray will not mark it dirty. If you want to mark if dirty, call markAsDirty().

@returnsvoid

insert

void

Insert a new AbstractControl at the given index in the array.

@paramindexnumber

Index in the array to insert the control. If index is negative, wraps around from the back. If index is greatly negative (less than -length), prepends to the array. This behavior is the same as Array.splice(index, 0, control).

@paramcontrolTControl

Form control to be inserted

@paramoptions{ emitEvent?: boolean | undefined; }

Specifies whether this FormArray instance should emit events after a new control is inserted.

emitEvent: When true or not supplied (the default), both the statusChanges and valueChanges observables emit events with the latest status and value when the control is inserted. When false, no events are emitted.

NOTE: Inserting to the FormArray will not mark it dirty. If you want to mark if dirty, call markAsDirty().

@returnsvoid

removeAt

void

Remove the control at the given index in the array.

@paramindexnumber

Index in the array to remove the control. If index is negative, wraps around from the back. If index is greatly negative (less than -length), removes the first element. This behavior is the same as Array.splice(index, 1).

@paramoptions{ emitEvent?: boolean | undefined; }

Specifies whether this FormArray instance should emit events after a control is removed.

emitEvent: When true or not supplied (the default), both the statusChanges and valueChanges observables emit events with the latest status and value when the control is removed. When false, no events are emitted.

NOTE: Removing the FormArray will not mark it dirty. If you want to mark if dirty, call markAsDirty().

@returnsvoid

setControl

void

Replace an existing control.

@paramindexnumber

Index in the array to replace the control. If index is negative, wraps around from the back. If index is greatly negative (less than -length), replaces the first element. This behavior is the same as Array.splice(index, 1, control).

@paramcontrolTControl

The AbstractControl control to replace the existing control

@paramoptions{ emitEvent?: boolean | undefined; }

Specifies whether this FormArray instance should emit events after an existing control is replaced with a new one.

emitEvent: When true or not supplied (the default), both the statusChanges and valueChanges observables emit events with the latest status and value when the control is replaced with a new one. When false, no events are emitted.

@returnsvoid

length

number

Length of the control array.

setValue

void

Sets the value of the FormArray. It accepts an array that matches the structure of the control.

This method performs strict checks, and throws an error if you try to set the value of a control that doesn't exist or if you exclude the value of a control.

@paramvalueɵIsAny<TControl, any[], ɵRawValue<TControl>[]>

Array of values for the controls

@paramoptions{ onlySelf?: boolean | undefined; emitEvent?: boolean | undefined; }

Configure options that determine how the control propagates changes and emits events after the value changes

onlySelf: When true, each change only affects this control, and not its parent. Default is false.
emitEvent: When true or not supplied (the default), both the statusChanges and valueChanges observables emit events with the latest status and value when the control value is updated. When false, no events are emitted. The configuration options are passed to the * updateValueAndValidity method.

@returnsvoid

Usage notes

Set the values for the controls in the form array

const arr = new FormArray([  new FormControl(),  new FormControl()]);console.log(arr.value);   // [null, null]arr.setValue(['Nancy', 'Drew']);console.log(arr.value);   // ['Nancy', 'Drew']

patchValue

void

Patches the value of the FormArray. It accepts an array that matches the structure of the control, and does its best to match the values to the correct controls in the group.

It accepts both super-sets and sub-sets of the array without throwing an error.

@paramvalueɵIsAny<TControl, any[], ɵValue<TControl>[]>

Array of latest values for the controls

@paramoptions{ onlySelf?: boolean | undefined; emitEvent?: boolean | undefined; }

Configure options that determine how the control propagates changes and emits events after the value changes

onlySelf: When true, each change only affects this control, and not its parent. Default is false.
emitEvent: When true or not supplied (the default), both the statusChanges and valueChanges observables emit events with the latest status and value when the control value is updated. When false, no events are emitted. The configuration options are passed to the updateValueAndValidity method.

@returnsvoid

Usage notes

Patch the values for controls in a form array

const arr = new FormArray([   new FormControl(),   new FormControl()]);console.log(arr.value);   // [null, null]arr.patchValue(['Nancy']);console.log(arr.value);   // ['Nancy', null]

reset

void

Resets the FormArray and all descendants are marked pristine and untouched, and the value of all descendants to null or null maps.

You reset to a specific form state by passing in an array of states that matches the structure of the control. The state is a standalone value or a form state object with both a value and a disabled status.

@paramvalueɵTypedOrUntyped<TControl, ɵIsAny<TControl, any[], ɵValue<TControl>[]>, any>

Array of values for the controls

@paramoptions{ onlySelf?: boolean | undefined; emitEvent?: boolean | undefined; }

Configure options that determine how the control propagates changes and emits events after the value changes

onlySelf: When true, each change only affects this control, and not its parent. Default is false.
emitEvent: When true or not supplied (the default), both the statusChanges and valueChanges observables emit events with the latest status and value when the control is reset. When false, no events are emitted. The configuration options are passed to the * updateValueAndValidity method.

@returnsvoid

Usage notes

Reset the values in a form array

const arr = new FormArray([   new FormControl(),   new FormControl()]);arr.reset(['name', 'last name']);console.log(arr.value);  // ['name', 'last name']

Reset the values in a form array and the disabled status for the first control

arr.reset([  {value: 'name', disabled: true},  'last']);console.log(arr.value);  // ['last']console.log(arr.at(0).status);  // 'DISABLED'

getRawValue

ɵIsAny<TControl, any[], ɵRawValue<TControl>[]>

The aggregate value of the array, including any disabled controls.

Reports all values regardless of disabled status.

@returnsɵIsAny<TControl, any[], ɵRawValue<TControl>[]>

clear

void

Remove all controls in the FormArray.

@paramoptions{ emitEvent?: boolean | undefined; }

Specifies whether this FormArray instance should emit events after all controls are removed.

emitEvent: When true or not supplied (the default), both the statusChanges and valueChanges observables emit events with the latest status and value when all controls in this FormArray instance are removed. When false, no events are emitted.

@returnsvoid

Usage notes

Remove all elements from a FormArray

const arr = new FormArray([   new FormControl(),   new FormControl()]);console.log(arr.length);  // 2arr.clear();console.log(arr.length);  // 0

It's a simpler and more efficient alternative to removing all elements one by one:

const arr = new FormArray([   new FormControl(),   new FormControl()]);while (arr.length) {   arr.removeAt(0);}

value

TValue

The current value of the control.

For a FormControl, the current value.
For an enabled FormGroup, the values of enabled controls as an object with a key-value pair for each member of the group.
For a disabled FormGroup, the values of all controls as an object with a key-value pair for each member of the group.
For a FormArray, the values of enabled controls as an array.

validator

ValidatorFn | null

Returns the function that is used to determine the validity of this control synchronously. If multiple validators have been added, this will be a single composed function. See Validators.compose() for additional information.

validator

ValidatorFn | null

asyncValidator

AsyncValidatorFn | null

Returns the function that is used to determine the validity of this control asynchronously. If multiple validators have been added, this will be a single composed function. See Validators.compose() for additional information.

asyncValidator

AsyncValidatorFn | null

parent

FormArray<any> | FormGroup<any> | null

The parent control.

status

FormControlStatus

The validation status of the control.

valid

boolean

A control is valid when its status is VALID.

invalid

boolean

A control is invalid when its status is INVALID.

pending

boolean

A control is pending when its status is PENDING.

disabled

boolean

A control is disabled when its status is DISABLED.

Disabled controls are exempt from validation checks and are not included in the aggregate value of their ancestor controls.

enabled

boolean

A control is enabled as long as its status is not DISABLED.

errors

ValidationErrors | null

An object containing any errors generated by failing validation, or null if there are no errors.

pristine

boolean

A control is pristine if the user has not yet changed the value in the UI.

dirty

boolean

A control is dirty if the user has changed the value in the UI.

touched

boolean

True if the control is marked as touched.

A control is marked touched once the user has triggered a blur event on it.

untouched

boolean

True if the control has not been marked as touched

A control is untouched if the user has not yet triggered a blur event on it.

events

any

A multicasting observable that emits an event every time the state of the control changes. It emits for value, status, pristine or touched changes.

Note: On value change, the emit happens right after a value of this control is updated. The value of a parent control (for example if this FormControl is a part of a FormGroup) is updated later, so accessing a value of a parent control (using the value property) from the callback of this event might result in getting a value that has not been updated yet. Subscribe to the events of the parent control instead. For other event types, the events are emitted after the parent control has been updated.

valueChanges

Observable<TValue>

A multicasting observable that emits an event every time the value of the control changes, in the UI or programmatically. It also emits an event each time you call enable() or disable() without passing along {emitEvent: false} as a function argument.

Note: the emit happens right after a value of this control is updated. The value of a parent control (for example if this FormControl is a part of a FormGroup) is updated later, so accessing a value of a parent control (using the value property) from the callback of this event might result in getting a value that has not been updated yet. Subscribe to the valueChanges event of the parent control instead.

statusChanges

Observable<FormControlStatus>

A multicasting observable that emits an event every time the validation status of the control recalculates.

updateOn

FormHooks

Reports the update strategy of the AbstractControl (meaning the event on which the control updates itself). Possible values: 'change' | 'blur' | 'submit' Default value: 'change'

setValidators

void

Sets the synchronous validators that are active on this control. Calling this overwrites any existing synchronous validators.

When you add or remove a validator at run time, you must call updateValueAndValidity() for the new validation to take effect.

If you want to add a new validator without affecting existing ones, consider using addValidators() method instead.

@paramvalidatorsValidatorFn | ValidatorFn[] | null

@returnsvoid

setAsyncValidators

void

Sets the asynchronous validators that are active on this control. Calling this overwrites any existing asynchronous validators.

When you add or remove a validator at run time, you must call updateValueAndValidity() for the new validation to take effect.

If you want to add a new validator without affecting existing ones, consider using addAsyncValidators() method instead.

@paramvalidatorsAsyncValidatorFn | AsyncValidatorFn[] | null

@returnsvoid

addValidators

void

Add a synchronous validator or validators to this control, without affecting other validators.

When you add or remove a validator at run time, you must call updateValueAndValidity() for the new validation to take effect.

Adding a validator that already exists will have no effect. If duplicate validator functions are present in the validators array, only the first instance would be added to a form control.

@paramvalidatorsValidatorFn | ValidatorFn[]

The new validator function or functions to add to this control.

@returnsvoid

addAsyncValidators

void

Add an asynchronous validator or validators to this control, without affecting other validators.

When you add or remove a validator at run time, you must call updateValueAndValidity() for the new validation to take effect.

Adding a validator that already exists will have no effect.

@paramvalidatorsAsyncValidatorFn | AsyncValidatorFn[]

The new asynchronous validator function or functions to add to this control.

@returnsvoid

removeValidators

void

Remove a synchronous validator from this control, without affecting other validators. Validators are compared by function reference; you must pass a reference to the exact same validator function as the one that was originally set. If a provided validator is not found, it is ignored.

@paramvalidatorsValidatorFn | ValidatorFn[]

The validator or validators to remove.

@returnsvoid

Usage notes

Reference to a ValidatorFn

// Reference to the RequiredValidatorconst ctrl = new FormControl<string | null>('', Validators.required);ctrl.removeValidators(Validators.required);// Reference to anonymous function inside MinValidatorconst minValidator = Validators.min(3);const ctrl = new FormControl<string | null>('', minValidator);expect(ctrl.hasValidator(minValidator)).toEqual(true)expect(ctrl.hasValidator(Validators.min(3))).toEqual(false)ctrl.removeValidators(minValidator);

When you add or remove a validator at run time, you must call updateValueAndValidity() for the new validation to take effect.

removeAsyncValidators

void

Remove an asynchronous validator from this control, without affecting other validators. Validators are compared by function reference; you must pass a reference to the exact same validator function as the one that was originally set. If a provided validator is not found, it is ignored.

When you add or remove a validator at run time, you must call updateValueAndValidity() for the new validation to take effect.

@paramvalidatorsAsyncValidatorFn | AsyncValidatorFn[]

The asynchronous validator or validators to remove.

@returnsvoid

hasValidator

boolean

Check whether a synchronous validator function is present on this control. The provided validator must be a reference to the exact same function that was provided.

@paramvalidatorValidatorFn

The validator to check for presence. Compared by function reference.

@returnsboolean

Usage notes

Reference to a ValidatorFn

// Reference to the RequiredValidatorconst ctrl = new FormControl<number | null>(0, Validators.required);expect(ctrl.hasValidator(Validators.required)).toEqual(true)// Reference to anonymous function inside MinValidatorconst minValidator = Validators.min(3);const ctrl = new FormControl<number | null>(0, minValidator);expect(ctrl.hasValidator(minValidator)).toEqual(true)expect(ctrl.hasValidator(Validators.min(3))).toEqual(false)

hasAsyncValidator

boolean

Check whether an asynchronous validator function is present on this control. The provided validator must be a reference to the exact same function that was provided.

@paramvalidatorAsyncValidatorFn

The asynchronous validator to check for presence. Compared by function reference.

@returnsboolean

clearValidators

void

Empties out the synchronous validator list.

When you add or remove a validator at run time, you must call updateValueAndValidity() for the new validation to take effect.

@returnsvoid

clearAsyncValidators

void

Empties out the async validator list.

When you add or remove a validator at run time, you must call updateValueAndValidity() for the new validation to take effect.

@returnsvoid

markAsTouched

2 overloads

Marks the control as touched. A control is touched by focus and blur events that do not change the value.

@paramopts{ onlySelf?: boolean | undefined; emitEvent?: boolean | undefined; } | undefined

Configuration options that determine how the control propagates changes and emits events after marking is applied.

onlySelf: When true, mark only this control. When false or not supplied, marks all direct ancestors. Default is false.
emitEvent: When true or not supplied (the default), the events observable emits a TouchedChangeEvent with the touched property being true. When false, no events are emitted.

@returnsvoid

@paramopts

{ onlySelf?: boolean | undefined; emitEvent?: boolean | undefined; sourceControl?: AbstractControl<any, any, any> | undefined; } | undefined

@returnsvoid

markAllAsDirty

void

Marks the control and all its descendant controls as dirty.

@paramopts{ emitEvent?: boolean | undefined; }

Configuration options that determine how the control propagates changes and emits events after marking is applied.

emitEvent: When true or not supplied (the default), the events observable emits a PristineChangeEvent with the pristine property being false. When false, no events are emitted.

@returnsvoid

markAllAsTouched

void

Marks the control and all its descendant controls as touched.

@paramopts{ emitEvent?: boolean | undefined; }

Configuration options that determine how the control propagates changes and emits events after marking is applied.

emitEvent: When true or not supplied (the default), the events observable emits a TouchedChangeEvent with the touched property being true. When false, no events are emitted.

@returnsvoid

markAsUntouched

2 overloads

Marks the control as untouched.

If the control has any children, also marks all children as untouched and recalculates the touched status of all parent controls.

@paramopts{ onlySelf?: boolean | undefined; emitEvent?: boolean | undefined; } | undefined

Configuration options that determine how the control propagates changes and emits events after the marking is applied.

onlySelf: When true, mark only this control. When false or not supplied, marks all direct ancestors. Default is false.
emitEvent: When true or not supplied (the default), the events observable emits a TouchedChangeEvent with the touched property being false. When false, no events are emitted.

@returnsvoid

@paramopts

{ onlySelf?: boolean | undefined; emitEvent?: boolean | undefined; sourceControl?: AbstractControl<any, any, any> | undefined; }

@returnsvoid

markAsDirty

2 overloads

Marks the control as dirty. A control becomes dirty when the control's value is changed through the UI; compare markAsTouched.

@paramopts{ onlySelf?: boolean | undefined; emitEvent?: boolean | undefined; } | undefined

Configuration options that determine how the control propagates changes and emits events after marking is applied.

onlySelf: When true, mark only this control. When false or not supplied, marks all direct ancestors. Default is false.
emitEvent: When true or not supplied (the default), the events observable emits a PristineChangeEvent with the pristine property being false. When false, no events are emitted.

@returnsvoid

@paramopts

{ onlySelf?: boolean | undefined; emitEvent?: boolean | undefined; sourceControl?: AbstractControl<any, any, any> | undefined; }

@returnsvoid

markAsPristine

2 overloads

Marks the control as pristine.

If the control has any children, marks all children as pristine, and recalculates the pristine status of all parent controls.

@paramopts{ onlySelf?: boolean | undefined; emitEvent?: boolean | undefined; } | undefined

Configuration options that determine how the control emits events after marking is applied.

onlySelf: When true, mark only this control. When false or not supplied, marks all direct ancestors. Default is false.
emitEvent: When true or not supplied (the default), the events observable emits a PristineChangeEvent with the pristine property being true. When false, no events are emitted.

@returnsvoid

@paramopts

{ onlySelf?: boolean | undefined; emitEvent?: boolean | undefined; sourceControl?: AbstractControl<any, any, any> | undefined; }

@returnsvoid

markAsPending

2 overloads

Marks the control as pending.

A control is pending while the control performs async validation.

@paramopts{ onlySelf?: boolean | undefined; emitEvent?: boolean | undefined; } | undefined

Configuration options that determine how the control propagates changes and emits events after marking is applied.

onlySelf: When true, mark only this control. When false or not supplied, marks all direct ancestors. Default is false.
emitEvent: When true or not supplied (the default), the statusChanges observable emits an event with the latest status the control is marked pending and the events observable emits a StatusChangeEvent with the status property being PENDING When false, no events are emitted.

@returnsvoid

@paramopts

{ onlySelf?: boolean | undefined; emitEvent?: boolean | undefined; sourceControl?: AbstractControl<any, any, any> | undefined; }

@returnsvoid

disable

2 overloads

Disables the control. This means the control is exempt from validation checks and excluded from the aggregate value of any parent. Its status is DISABLED.

If the control has children, all children are also disabled.

@paramopts{ onlySelf?: boolean | undefined; emitEvent?: boolean | undefined; } | undefined

Configuration options that determine how the control propagates changes and emits events after the control is disabled.

onlySelf: When true, mark only this control. When false or not supplied, marks all direct ancestors. Default is false.
emitEvent: When true or not supplied (the default), the statusChanges, valueChanges and events observables emit events with the latest status and value when the control is disabled. When false, no events are emitted.

@returnsvoid

@paramopts

{ onlySelf?: boolean | undefined; emitEvent?: boolean | undefined; sourceControl?: AbstractControl<any, any, any> | undefined; }

@returnsvoid

enable

void

Enables the control. This means the control is included in validation checks and the aggregate value of its parent. Its status recalculates based on its value and its validators.

By default, if the control has children, all children are enabled.

@paramopts{ onlySelf?: boolean | undefined; emitEvent?: boolean | undefined; }

Configure options that control how the control propagates changes and emits events when marked as untouched

onlySelf: When true, mark only this control. When false or not supplied, marks all direct ancestors. Default is false.
emitEvent: When true or not supplied (the default), the statusChanges, valueChanges and events observables emit events with the latest status and value when the control is enabled. When false, no events are emitted.

@returnsvoid

setParent

void

Sets the parent of the control

@paramparentFormArray<any> | FormGroup<any> | null

The new parent.

@returnsvoid

updateValueAndValidity

2 overloads

Recalculates the value and validation status of the control.

By default, it also updates the value and validity of its ancestors.

@paramopts{ onlySelf?: boolean | undefined; emitEvent?: boolean | undefined; } | undefined

Configuration options determine how the control propagates changes and emits events after updates and validity checks are applied.

onlySelf: When true, only update this control. When false or not supplied, update all direct ancestors. Default is false.
emitEvent: When true or not supplied (the default), the statusChanges, valueChanges and events observables emit events with the latest status and value when the control is updated. When false, no events are emitted.

@returnsvoid

@paramopts

{ onlySelf?: boolean | undefined; emitEvent?: boolean | undefined; sourceControl?: AbstractControl<any, any, any> | undefined; }

@returnsvoid

setErrors

2 overloads

Sets errors on a form control when running validations manually, rather than automatically.

Calling setErrors also updates the validity of the parent control.

Note: Manually set errors are always overwritten by the results of the next validation run.

@paramerrorsValidationErrors | null

@paramopts{ emitEvent?: boolean | undefined; } | undefined

Configuration options that determine how the control propagates changes and emits events after the control errors are set.

emitEvent: When true or not supplied (the default), the statusChanges observable emits an event after the errors are set.

@returnsvoid

Usage notes

Manually set the errors for a control

const login = new FormControl('someLogin');login.setErrors({  notUnique: true});expect(login.valid).toEqual(false);expect(login.errors).toEqual({ notUnique: true });login.setValue('someOtherLogin');expect(login.valid).toEqual(true);

@paramerrorsValidationErrors | null

@paramopts{ emitEvent?: boolean | undefined; shouldHaveEmitted?: boolean | undefined; } | undefined

@returnsvoid

get

2 overloads

Retrieves a child control given the control's name or path.

This signature for get supports strings and const arrays (.get(['foo', 'bar'] as const)).

@parampathP

@returnsAbstractControl<ɵGetProperty<TRawValue, P>, ɵGetProperty<TRawValue, P>, any> | null

Retrieves a child control given the control's name or path.

This signature for get supports non-const (mutable) arrays. Inferred type information will not be as robust, so prefer to pass a readonly array if possible.

@parampathP

@returnsAbstractControl<ɵGetProperty<TRawValue, P>, ɵGetProperty<TRawValue, P>, any> | null

getError

any

Reports error data for the control with the given path.

@paramerrorCodestring

The code of the error to check

@parampathstring | (string | number)[] | undefined

A list of control names that designates how to move from the current control to the control that should be queried for errors.

@returnsany

Usage notes

For example, for the following FormGroup:

form = new FormGroup({  address: new FormGroup({ street: new FormControl() })});

The path to the 'street' control from the root form would be 'address' -> 'street'.

It can be provided to this method in one of two formats:

An array of string control names, e.g. ['address', 'street']
A period-delimited list of control names in one string, e.g. 'address.street'

hasError

boolean

Reports whether the control with the given path has the error specified.

@paramerrorCodestring

The code of the error to check

@parampathstring | (string | number)[] | undefined

A list of control names that designates how to move from the current control to the control that should be queried for errors.

@returnsboolean

Usage notes

For example, for the following FormGroup:

form = new FormGroup({  address: new FormGroup({ street: new FormControl() })});

The path to the 'street' control from the root form would be 'address' -> 'street'.

It can be provided to this method in one of two formats:

An array of string control names, e.g. ['address', 'street']
A period-delimited list of control names in one string, e.g. 'address.street'

If no path is given, this method checks for the error on the current control.

root

AbstractControl<any, any, any>

Retrieves the top-level ancestor of this control.

Description

Tracks the value and validity state of an array of FormControl, FormGroup or FormArray instances.

A FormArray aggregates the values of each child FormControl into an array. It calculates its status by reducing the status values of its children. For example, if one of the controls in a FormArray is invalid, the entire array becomes invalid.

FormArray accepts one generic argument, which is the type of the controls inside. If you need a heterogenous array, use UntypedFormArray.

FormArray is one of the four fundamental building blocks used to define forms in Angular, along with FormControl, FormGroup, and FormRecord.

Usage Notes

Create an array of form controls

const arr = new FormArray([  new FormControl('Nancy', Validators.minLength(2)),  new FormControl('Drew'),]);console.log(arr.value);   // ['Nancy', 'Drew']console.log(arr.status);  // 'VALID'

Create a form array with array-level validators

You include array-level validators and async validators. These come in handy when you want to perform validation that considers the value of more than one child control.

The two types of validators are passed in separately as the second and third arg respectively, or together as part of an options object.

const arr = new FormArray([  new FormControl('Nancy'),  new FormControl('Drew')], {validators: myValidator, asyncValidators: myAsyncValidator});

Set the updateOn property for all controls in a form array

The options object is used to set a default value for each child control's updateOn property. If you set updateOn to 'blur' at the array level, all child controls default to 'blur', unless the child has explicitly specified a different updateOn value.

const arr = new FormArray([   new FormControl()], {updateOn: 'blur'});

Adding or removing controls from a form array

To change the controls in the array, use the push, insert, removeAt or clear methods in FormArray itself. These methods ensure the controls are properly tracked in the form's hierarchy. Do not modify the array of AbstractControls used to instantiate the FormArray directly, as that result in strange and unexpected behavior such as broken change detection.