How to pass value of selected variable from php script to javascript (ajax)?

Question

PHP

Good afternoon!
The question of how to send a specific value of a variable from a php script to ajax as a response is very interesting.
There is a feedback form that accepts data via ajax. In the php script, in addition to the function for processing the data received from the form, there are also others, so if you return

success: function(res) {
    ...
}

then all-all variables from this script will be displayed.

And how to pass the specific value of the $perem variable from the given php script as a response?

Answer 1

echo json_encode( array('perem' => $perem));

Answer 2

echo $perem