https://angular.io › api › forms › Validators

A validator is a function that processes a FormControl or collection of controls and returns an error map or null. A null map means that validation has passed. Static methods link. Provides a set of built-in validators that can be used by form controls.

https://angular.dev › guide › forms › form-validation

You can improve overall data quality by validating user input for accuracy and completeness. This page shows how to validate user input from the UI and display useful validation messages, in both reactive and template-driven forms.

https://angular.dev › api › forms › Validators

Provides a set of built-in validators that can be used by form controls. Form Validation. API. Description. class Validators { static min(min: number): ValidatorFn; static max(max: number): ValidatorFn; static required(control: AbstractControl <any, any>): ValidationErrors; static requiredTrue(control: AbstractControl <any, any>): ValidationErrors;

https://angular.fr › reactive-forms › validator

Voici comment vous pouvez utiliser la propriété validators pour ajouter des validateurs aux contrôles FormControl dans l'exemple de code LoginFormComponent : ts.

https://stackoverflow.com › questions › 38797414

Since Angular 12, if you want to add new validators to the form without removing the existing validators, you can use addValidator: this.form.controls["firstName"].addValidators([Validators.minLength(1), Validators.maxLength(30)]);

https://angular.dev › tutorials › learn-angular › 18-forms-validation

Every FormControl can be passed the Validators you want to use for validating the FormControl values. For example, if you want to make the name field in profileForm required then use Validators.required.

https://blog.angular-university.io › angular-custom-validators

In this post, you will learn everything that you need to know in order to implement your own custom form validators, including both synchronous and asynchronous, field-level, form-level, and both for template-driven and reactive forms.

https://angular.io › api › forms › FormControl

This is one of the four fundamental building blocks of Angular forms, along with FormGroup, FormArray and FormRecord. It extends the AbstractControl class that implements most of the base functionality for accessing the value, validation status, user interactions and events.

https://stackoverflow.com › questions › 43838108

If you want to check if a controller has a certain validators, it is very simple for angular 12.2+. for example, let controller = new FormControl('', [Validators.required]) console.log(controller.hasValidator(Validators.required))//true.