Make Order notes field required only when it is not hidden in Woocommerce checkout - php

Question

In Woocommerce checkout page, I have managed to show or hide "Order notes" field when "ship-to-different-address" checkbox is checked or unchecked, using "Show hide Order notes field based on a checkbox in Woocommerce checkout" answer code to one of my questions.
I would like "Order notes" field to be required only when it's visible.
How can I make this "Order notes" field required when it's visible (not hidden) and enable the validation for it?
Any help is welcome.

Answer 1

The following code will make "Order notes" field to be required only when it's not hidden and will enable in this case the field validation.
Note (mandatory): The "Order notes" field has to be optional (just as in default Woocommerce), without that the code will not work properly.
The complete code:
// Remove "(optional)" label on "Order notes" field
add_filter( 'woocommerce_form_field' , 'remove_order_comments_optional_fields_label', 10, 4 );
function remove_order_comments_optional_fields_label( $field, $key, $args, $value ) {
// Only on checkout page for Order notes field
if( 'order_comments' === $key && is_checkout() ) {
$optional = ' <span class="optional">(' . esc_html__( 'optional', 'woocommerce' ) . ')</span>';
$field = str_replace( $optional, '', $field );
}
return $field;
}
// The jQuery script that show hide "Order notes" field
add_action( 'woocommerce_after_order_notes', 'custom_checkout_scripts_js_script', 10, 1 );
function custom_checkout_scripts_js_script( $checkout ) {
$required = esc_html__( 'required', 'woocommerce' );
?>
<script type="text/javascript">
(function($){
var required = '<abbr class="required" title="<?php echo $required; ?>">*</abbr>',
notesField = '#order_comments_field',
shipCheckbox = '#ship-to-different-address-checkbox';
function actionRequire( actionToDo='yes', selector='' ){
if ( actionToDo == 'yes' ) {
$(selector).addClass("validate-required");
$(selector+' label').append(required);
} else {
$(selector).removeClass("validate-required");
$(selector+' label > .required').remove();
}
$(selector).removeClass("woocommerce-validated");
$(selector).removeClass("woocommerce-invalid woocommerce-invalid-required-field");
}
// On load and on form change
$('form.checkout').on( 'change', shipCheckbox, function(){
if( $(this).prop('checked') === true ) {
$(notesField).hide(); // Show
actionRequire( 'no' ,notesField );
} else {
$(notesField).show(); // Hide
actionRequire( 'yes' ,notesField );
}
});
})(jQuery);
</script>
<?php
}
// "Order notes" field validation
add_action('woocommerce_checkout_process', 'order_comments_field_validation');
function order_comments_field_validation() {
if ( isset($_POST['order_comments']) && empty($_POST['ship_to_different_address']) )
wc_add_notice( __( 'Please fill in "Order notes" required field.' ), 'error' );
}
Code goes on function.php file of your active child theme (or active theme). Tested and works.
Similar: Make Woocommerce checkout phone field optional based on shipping country
Related: Show hide Order notes field based on a checkbox in Woocommerce checkout