语法错误：输入ajax的意外结束

Question

我有这个让我回复的ajax请求：

  

语法输入ajax的意外结束错误

$.ajax({

    url: "file.php",
    type: 'POST',
    dataType: "json",
    data: {
        string : name
    },
    success: function(data, textStatus, xhr) {

        toastr.success(data, "Ok");

    },
    error: function(xhr, textStatus, errorThrown) {

        toastr.error("Error: " + xhr + " error thrown: " + errorThrown+ " error " + errorThrown, "Error");

    }

});

file.php 就是这个：

    $string_to_found = $_POST['string'];

    $file_xml = "../file.xml";
    if (!file_exists($file_xml)) {

        echo json_encode(array("response" => "no_file", "message"=>"File Not Found"));

    } else {

        $xml = simplexml_load_file($file_xml );

        $number = count($xml);

        for ($num = 0; $num < $number; $num++) {

            $row++;
            $filearray[] = array(
                "cod" => (string)$xml->record[$num]->value,
                "com" => (string)$xml->record[$num]->name,
            );

        }

        foreach($filearray as $item){

            if($item['com'] == $string_to_found ) {

                echo json_encode(array("response" => "ok", "message"=>"Code Found", "code" => $item['cod']));

            } 

        }

    }

file.php给了我正确的值：

{"response":"ok","message":"Code Found","cod":"AA019"}

我如何解决这个问题？我试图用echo改变php print，也改变dataType和contentType