<input id="star5" name="star" type="radio" value="100" class="radio-btn hide" />
<label for="star5">☆</label>

<input id="star4" name="star" type="radio" value="80"
    class="radio-btn hide" />
<label for="star4">☆</label>

<input id="star3" name="star" type="radio" value="60"
    class="radio-btn hide" />
<label for="star3">☆</label>

<input id="star2" name="star" type="radio" value="40"
    class="radio-btn hide" />
<label for="star2">☆</label>

<input id="star1" name="star" type="radio" value="20"
    class="radio-btn hide" />
<label for="star1">☆</label>

<button type="submit" class="btn btn-block btn-main" id="commentbtn" onclick="comment()" > Send </button>

function comment() {
        var comment = $('#comment').val();
        var star = $('input[name=star]').val();
        var product_id = '<?php echo $productID;?>';
        var username = '<?php echo $_SESSION["username"];?>';
        jQuery.ajax({
            url: "comment.php",
            data: {
                comment: comment,
                product_id: product_id,
                star: star,
                username: username
            },
            type: "POST",
            success: function(data) {
                swal({
                    text: "comment has been submitted",
                    icon: "success",
                    button: false,
                    timer: 1500,
                });
                $(document).ready(function(e) {
                    setTimeout(function() {
                        window.location.href = "single.php?product_id=" + product_id
                    }, 1500)
                });
            },
            error: function() {}
        });
    }