Can I make the postal code a required field?

You need to edit two files in order to get the new “required” fields working. First file is /wp-content/plugins/speakout/includes/emailpetition.php and the second file is /wp-content/plugins/speakout/js/public.js

The first file: emailpetition.php

The following steps are required in order to make the field “required”.

Find the following line.

<label for=”dk-speakout-postcode-‘ . $petition->id . ‘”>’ . __( ‘Postal Code’, ‘speakout’ ) . ‘</label>

Change this line to;
<label for=”dk-speakout-postcode-‘ . $petition->id . ‘” class=”required”‘ . ‘>’ . __( ‘Postal Code’, ‘speakout’ ) . ‘</label>

The second file public.js

Find the following lines:

if ( lastname === ” ) {
$( ‘#dk-speakout-last-name-‘ + id ).addClass( ‘dk-speakout-error’ );
errors ++;
}

Append the following code just after this section .

if ( postcode === ” ) {
$( ‘#dk-speakout-postcode-‘ + id ).addClass( ‘dk-speakout-error’ );
errors ++;
}

So it should look like this:

if ( lastname === ” ) {
$( ‘#dk-speakout-last-name-‘ + id ).addClass( ‘dk-speakout-error’ );
errors ++;
}
if ( postcode === ” ) {
$( ‘#dk-speakout-postcode-‘ + id ).addClass( ‘dk-speakout-error’ );
errors ++;
}

(Thanks to @altinkaya)