Verify input before post

Hi,

How can i verify inputs ? And when i click on button’s send and the input are empty an error alert shown up ?

My submit button goes to a submit handler that checks the form validators, and either pops the errors if the form is not valid, or proceeds to the “real” handler: a separate procedure that handles the form. You can pop the errors with a showErrors boolean flag, and in your template use *ngIf.