Angular 12 References/ Forms
🍀 Angular References

[maxlength] validation directive

A directive that adds max length validation to controls marked with the maxlength attribute. The directive is provided with the NG_VALIDATORS multi-provider list.

Adding a maximum length validator

The following example shows how to add a maximum length validator to an input attached to an ngModel binding.

<input name="firstName" ngModel maxlength="25">

maxlength#

@Input() maxlength: string|number

Tracks changes to the maximum length bound to this directive.

validate#

validate(control: AbstractControl): ValidationErrors|null

Method that validates whether the value exceeds the maximum length requirement.

registerOnValidatorChange#

registerOnValidatorChange(fn: () => void): void

Registers a callback function to call when the validator inputs change.