jQuery Ajax(post), data not being received by PHP - php

Question

The Ajax function below sends data from a page to the same page where it is interpreted by PHP.
Using Firebug we can see that the data is sent, however it is not received by the PHP page. If we change it to a $.get function and $_GET the data in PHP then it works.
Why does it not work with $.post and $_POST
$.ajax({
type: "POST",
url: 'http://www.example.com/page-in-question',
data: obj,
success: function(data){ alert(data)},
dataType: 'json'
});

Answer 1

if there is a problem, it probably in your php page.
Try to browse the php page directly in the browser and check what is your output.
If you need some inputs from post just change it to the GET in order to debug

Answer 2

try this
var sname = $("#sname").val();
var lname = $("#lname").val();
var html = $.ajax({
type: "POST",
url: "ajax.class.php",
data: "sname=" + sname +"&lname="+ lname ,
async: false
}).responseText;
if(html)
{
alert(html);
return false;
}
else
{
alert(html);
return true;
}
alax.class.php
<php
echo $_REQUEST['sname'];
echo $_REQUEST['sname'];
?>

Answer 3

Ajax on same page will not work to show data via POST etc because, PHP has already run that's why you would typically use the external page to process your data and then use ajax to grab the response.
example
success: function(){
$('#responseDiv').text(data);
}

Answer 4

You are posting the data... Check if the target is returning some data or not.
if it returns some data then only you can see the data otherwise not.
add both success and error.. so that you can get what exactly
success: function( data,textStatus,jqXHR ){
console.log(data);//if it returns any data
console.log(textStatus);//or alert(textStatus);
}
error: function( jqXHR,textStatus,errorThrown ){
console.log("There is some error");
console.log(errorThrown);
}