How to confirm before deleting a record with PHP and AlertifyJS?

First, you should not delete a record using a GET , you would use a POST (or a DELETE if it is an Api REST). Then, I would use a function in JS to delete the record using Ajax.

Create a button that has a data attribute with the id to be deleted.

<button type="button" class="elimina" data-becarioId="<?php echo $registro['id_becario']; ?>">Eliminar</button>

Then the JS, in the click event, gets the id that is associated with the button by means of the data attribute. You pass it by parameter to the function it eliminates.

$(document).ready(function() {

  $('.elimina').on('click', function() {
    var id = $(this).data('becarioId');
    eliminar(id);
  });

  var eliminar = function(id) {
    alertify.confirm("Deseas eliminar al usuario", function() {

      // confirma eliminar
      $.post('tu_url_para_eliminar.php', { becarioId: id }, function(data) {
        // se eliminó correctamente
        alertify.success('Usuario eliminado');
      }).fail(function() {
        // ocurrió un error
        alertify.error('Error al eliminar usuario');
      });

    });
  }

});

Method $ .post ()

Method $ .ajax () (full version of $.post() or $.get() )

Greetings I leave the code:

<!-- JavaScript -->
<script src="//cdn.jsdelivr.net/npm/[email protected]/build/alertify.min.js"></script>

<!-- CSS -->
<link rel="stylesheet" href="//cdn.jsdelivr.net/npm/[email protected]/build/css/alertify.min.css"/>
<form action="" onsubmit="return false" name="miFormulario">
<input type="text">
<input type="submit" value="Grabar Datos">
</form>
<script>
$(document).on('submit', 'form', function(e){

    alertify.confirm('Confirm Title', 'Confirm Message',
    function(){
    //submit
    document.miFormulario.submit();
    alertify.success('Ok') 
    },
    function(){ 
    alertify.error('Cancel')

    });
});


</script>

Explanation , inside the form:

<form action="" onsubmit="return false" name="miFormulario">

I stop the submit to control it by javascript, an additional name is assigned to the form that serves for once the action is confirmed, I send the form or I do the submit.

//submit
document.miFormulario.submit();

with that code what I do once confirmed the action of the alert I send the form or I force the submit.

'Confirm Title', 'Confirm Message',

that part serves to put the title of the alert and your message:

I hope you serve, I leave the link of the official documentation for more information. Documentation-Confirm