[Form to Post] Question about the code from the example

Hey, I was trying to add multiple content together to the post, and I saw the author already answered the question. However, the example code he gave has a small mistake (I think it is a mistake but it might not affect at all.) and i don’t know how to fix it.

<script type="text/javascript">
    (function($) {
        $(document).ready(function() {

            // CHANGE: list all field id's here
            $('#field1, #field2, #field3').change(function() {  

              // CHANGE: Format how you want the fields to come out in the post
               var content =
                     "Answer for Field 1 is: "+ $('#field1').val() + "<br/>" +
                     "Answer for Field 2 is: "+ $('#field2').val() + "<br/>" +
                     "Answer for Field 3 is: "+ $('#field3').val() + "<br/>";

                if ($('#post_content').length > 0) {
                    $('#post_content').val(content);
                }
                else {
                    var postContentInput = $("<input>").attr("type", "hidden").attr("name", "post_content").val(answer);
                    $(this).parents('form:first').append($(postContentInput));
                }
            });
        })
    })(jQuery);
</script>

So the line after else statement:
var postContentInput = $("<input>").attr("type", "hidden").attr("name", "post_content").val(answer);
There is no “answer” was declared in the variables.(It’s from the last post answer) However, I don’t know what I should put in to replace it since I will have more than one filed content(field1, field2, field3).

Could anyone help to fix the code? I am not very familiar with scrip code.

https://wordpress.org/support/plugin/form-to-post