数据不会通过ajax调用发布到后端

I am trying to post data to a php file through ajax call. But I could not get those data in my php file. It just returns the empty array when I check using var_dump($_POST). Anyone help me on this.

Here is my ajax script

<script>
    $.ajax({
                url: "update_user.php",
                type: 'post',
                data: {
                    "type": "active"
                },
                error: function (e) {
                },
                success: function(data) {

                }
            }); 
</script>

In update_user.php,

<?php
var_dump($_POST);
?>

It returns array(0) { }

I think type should be POST (uppercase not lower).

$.ajax({
            url: "update_user.php",
            type: "POST",
            data: {
                type: "active"
            },
            error: function (e) {
            },
            success: function(data) {

            }
        });