PHP Not catching ajax request - php

Question

I am having request like this:
$(function(){
$("#novaProfaktura").click(function(){
$.ajax({
type: "POST",
url: "../Pages/Program.php",
data: { action: "testing" },
success: function()
{
alert("Ajax done"); //Testing purpose
}
});
location.reload();
});
});
And then in my body I have php like this:
<div id="Content">
<?php
echo("Php running <br>");
if($_SERVER['REQUEST_METHOD'] == 'POST')
{
echo("Post running <br>");
if($_POST['action'] = "testing")
{
echo("Action running <br>");
}
}
?>
</div>
What I am getting from this is alert message so I assume ajax is set up properly and getting Php running but it doesn't pass if($_SERVER['REQUEST_METHOD'] == 'POST'
As you can see jQuery code is running on div click.
What am I doing wrong?
EDIT: I have used function(data) and it seems to work BUT it doesn't return only echoed data but WHOLE page with echo. I used document.write() and it rewrite whole page but how to get particular echo value?

Answer 1

Answer for this was to instead of this:
success: function()
{
alert("Ajax done"); //Testing purpose
}
use this:
success: function(data)
{
alert("Ajax done"); //Testing purpose
document.getDocumentById('emptyDiv').innerHTML = data;
}
Now as data you are getting all HTML text from document you are running function from so instead of url: "../Pages/Program.php" I used separated file url: "../Php/Testing.php" and inside that file I have
only this code:
<?php
echo("Testing");
?>

Answer 2

$_POST['action'] = "testing"
This is variable assignment
$_POST['action'] == "testing"
This is comparison. You want this.
$_POST['action'] === "testing"
This is better because it's type matching too, it must be a string.