problem passing variable to php file

I really dont know why this isnt working!

<script src="js/jquery.js" type="text/javascript" language="javascript"></script>

<script type="text/javascript">

function updateVA开发者_Python百科L()
{
var f = document.getElementById("nu");
var val=f.value;
alert(val); // it displays the value properly 
$.post("getDATA.php", {id: val}); // I sent the variable with jquery
}

</script>

getDATA.php

$value=$_POST['id'];
echo $value;

and when I access getDATA.php to see if it was sent I get this:

Notice: Undefined index: id in C:\Users\dan...

why the variable 'id' isnt set ? why is isnt passed to the server ?

Any help would be appreciated :) Cheers,

dan.

Parameters are being sent via ajax - so this js script calls getDATA.php and $_POST['id'] is "seen" there only at that time.

And you are trying to access getDATA.php after and send no post or get parameters by your briwser - so you don't see this params there.

You have to catch echo by your js script. Look at this demo:

$.post("test.php", { name: "John", time: "2pm" },
   function(data) {
     alert("Data Loaded: " + data);
   });