Change Select box value if checkbox is checked WordPress WooCommerce

I am trying to customize my WooCommerce checkout page. I have two shipping methods (express and standard) and in fields section I’ve also added delivery time select options in which I want to make changes according to the shipping method selected by user. By default my delivery time input select box have 2 options.
I want to decrease time interval from 3 hours to 1 hour if Express shipping method is selected.

    function custom_override_checkout_fields( $fields ) {

             switch( date("h:00" ) ){
                        case  date("h:00" ) != "19:00":
                    $fields['billing']['billing_time']['options'] = array(
                            'option_1' => date("h:00" ). " - " .date("h:00",strtotime('+3 hours')),
                            'option_2' => date("h:00",strtotime('+3 hours')). " - " .date("h:00",strtotime('+6 hours'))
                    );
                        break;
                }
                     return $fields;
            }

• This topic was modified 5 years, 8 months ago by akberovr.
• This topic was modified 5 years, 8 months ago by akberovr.

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