proof of payment

method.php

add_action( 'woocommerce_checkout_order_review', 'method_proof_of_payment', 10, 1 );
add_action( 'woocommerce_checkout_order_review', 'check_order', 10, 1 );

function method_proof_of_payment() {

echo "<script>
jQuery( document ).ajaxComplete(function() {

        if(jQuery('#payment_method_cod').is(\":checked\")){
            jQuery('label[for=\"wccf_checkout_field_proof_payment\"]').show();
            jQuery('#wccf_checkout_field_proof_payment').show();

        } else {
            jQuery('label[for=\"wccf_checkout_field_proof_payment\"]').hide();
            jQuery('#wccf_checkout_field_proof_payment').hide();
        }

    });
       
</script>";
}

function check_order() {
    echo "
<script>
jQuery(document).ready(function($) {
    jQuery(\"form.woocommerce-checkout\").on('submit', function(event) {
        if(jQuery('#payment_method_cod').is(\":checked\")){
        if( document.getElementById(\"wccf_checkout_field_proof_payment\").files.length == 0 ){
            event.preventDefault();
            alert(\"Please insert payment proof\");
        }
    }
    });
});</script>";
}