Need to pass variables with jquery $.post()
<p>I want to pass variable with jQuery <code>$.post()</code>.</p>

<p>My code</p>

<pre><code>$('#unit_id').change(function() {
        var unit_id = 'sdf';
        var user_id = 'werwe';
        $.post("test.php", { 'user_id': +user_id, 'unit_id': +unit_id, },
          function(data){
            console.log(data.user_id);
            console.log(data.unit_id);
          }, "json");
    });
</code></pre>

<p>But this post result like:</p>

<pre><code>unit_id NaN
user_id NaN
</code></pre>

<p>why this is <code>NaN</code>?</p>
