+1

Check this way:

rows.controls.splice(0)

As per https://angular.io/api/forms/FormArray#adding-or-removing-controls-from-a-form-array this is not recommended.

As per Adding or removing controls from a form array this is not recommended.

@renanmontebelo, yes, you are right. Now I am not recommended this way.

If we look at the source of removeAt() method, we can see that for properly way needed to use not only controls.splice().

As of Angular 8+ please use:

formArray.clear();

For previous versions the recommended way is

// updated based on trotyl comment
while (formArray.length) {
  formArray.removeAt(formArray.length-1);
}

@renanmontebelo Arrays are in consecutive memory, removing first element costs O(n), and the while loop becomes O(n^2), better to remove at end.

@trotyl you're absolutely right, thank you for your suggestion. I updated my comment based on your feedback.

While loop will take long time to delete all items if array has 100's of items. You can empty both controls and value properties of FormArray like below.

clearFormArray = (formArray: FormArray) => {
formArray.controls = [];
formArray.setValue([]);
}

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