how to get div's text to a variable - php

Question

what I mainly want to do is to get the div's content and pass it in a variable. To explain what I have done until now :
I have my php file that contains the code :
<?php
$connect = mysql_connect("localhost", "...","...") or die("Could not connect to the database.");
mysql_select_db("...") or die("Could not find database <...>");
$query = mysql_query("SELECT id FROM datainput WHERE id>=ALL(SELECT id FROM datainput)") or die("Query could not be executed");
$row = mysql_fetch_assoc($query);
echo $row['id'];
?>
In my index.php file I have written the following script :
<script type="text/javascript" src="jquery.js"></script>
<script type="text/javascript">
$("document").ready( function(){
//setInterval("checkForNewData()", 1000); //30 Minutes = 1800000 Milliseconds
checkForNewData();
});
function checkForNewData(){
$("#lastid").load("lastData.php");
var mydata = $("#lastid").text();
}
</script>
In my html tag I have a div with id="lastid".
With the code below :
var mydata = $("#lastid").text();
I want to keep the current text of lastid div, so I can later compare it with another.
As I have read here, this should have done mydata="6" (is the current result)?
What am I doing wrong?
Can anyone help? Pleaseee...

Answer 1

You need to wait for the load to have finished. This is done by using a callback function like so:
<script type="text/javascript">
$("document").ready( function(){
//setInterval("checkForNewData()", 1000); //30 Minutes = 1800000 Milliseconds
checkForNewData();
});
function checkForNewData(){
$("#lastid").load("lastData.php", function(){
var mydata = $("#lastid").text();
});
}
</script>
Please see the jQuery API docs for more information: http://api.jquery.com/load/
Essentially, the second argument of the load function can be a function. If it is, then whatever code is in that function will be executed when the load has completed.