为什么收到“ Uncaught SyntaxError：JSON输入意外结束”？

Question

<script type="text/javascript">
      setInterval(function() {

        $.ajax({
          type: "POST",
          url: "http://localhost/alaris/admin/product_notification",
          data: JSON.stringify({ product:"product"}),
          success: function(res) {
            $("#product_notify").html(res);
            //alert(res);
          }   
        });
     }, 5000);
    </script>

When I'm running the above code it displays following error message in the console

Uncaught SyntaxError: Unexpected end of JSON input
    at JSON.parse (<anonymous>)
    at Function.n.parseJSON (jQuery-2.1.4.min.js:4)
    at Object.success (custom.js:85)
    at j (jQuery-2.1.4.min.js:2)
    at Object.fireWith [as resolveWith] (jQuery-2.1.4.min.js:2)
    at x (jQuery-2.1.4.min.js:4)
    at XMLHttpRequest.<anonymous> (jQuery-2.1.4.min.js:4)
n.parseJSON @ jQuery-2.1.4.min.js:4
success @ custom.js:85
j @ jQuery-2.1.4.min.js:2
fireWith @ jQuery-2.1.4.min.js:2
x @ jQuery-2.1.4.min.js:4
(anonymous) @ jQuery-2.1.4.min.js:4

Can anyone would find what the error is?

Answer 1

如果product是对象：

JSON.stringify({ "product" : product })