jQuery AJAX和PHP没有获取数据值

Question

I am trying to fetch the values of the data variable passed with jQuery AJAX to a php page. How to solve it?

Below is the HTML page code:

<input id="name" placeholder="Enter your name." />
<button id="submit">Submit</button>
<div id="message"></div>

On the button click this jQuery AJAX calls a php page:

 $.ajax({
     type: "POST",
     url: "jquery-ajax-hello.php",
     contentType: "application/json; charset=utf-8",
     data: '{"name":"' + $("#name").val() + '"}',
     success: function (result, status, xhr) {
         $("#message").html(result);
     },
     error: function (xhr, status, error) {
         $("#message").html("Result: " + status + " " + error + " " + xhr.status + " " + xhr.statusText)
     }
 });

The PHP Page code is:

<?php
$name = $_POST['name'];
echo "Hello ".$name.", How are you ?"; 
?>

In the php page I am not able to fetch the data varaible 'name' value?

Please help?