AJAX , check for changes and do refresh!!

[canabatz]

i got this php file 'check.php' that checks for changes ,and showing a counter for posts !!

$show_data="SELECT * FROM bidding_main WHERE bid_id='$bid_id' ";
$show_data_query=mysql_query($show_data);
$num_show_data=mysql_num_rows($show_data_query);
        $sqlno="SELECT * FROM bidding_details WHERE bid_id=$bid_id ";
$queryno=mysql_query($sqlno);
        echo "<table width='517' border='0' cellspacing='0' cellpadding='0'>";
        echo "    <tr>";
         $rem=$max_bid-$numno;
                        if($rem<=0)
                        {
                        echo "0";
                        }
                        else
                        {
                        echo "<td bgcolor='#FFFFFF' align='center'><font color='red'><b>הצעות לסגירה: $rem </b></font></td>";
                        }"</td>";
        echo "</tr>";
        echo "</table>";

now, i cannot figure it out in ajax how to point the request to check if something as changed when the php file is executed?

how do i get the ajax to check that something as changed?

here is my starting ajax file

function loadXMLDoc(url, callBack) {
    if (window.XMLHttpRequest) {
        req = new XMLHttpRequest();
        req.onreadystatechange = callBack;
        req.open("POST", url, true);
        req.send(null);
    } else if (window.ActiveXObject) {
        req = new ActiveXObject("Microsoft.XMLHTTP");
        if (req) {
            req.onreadystatechange = callBack;
            req.open("POST", url, true);
            req.send();
        }
    }
}
 
 
 
 
 
function RefreshEngine( now)
{  
     var url="check.php"
     if (now) url+='';
 
     loadXMLDoc(url, RefreshResult;
 
}
 
 
 
function RefreshResult ()
 
{
 
    //here im goint to have the second result
 
}

please help me out with this ,it's a week that im serching for result for this ,i tryed million of combinations ,and no success !!

please help or point me to the right direction!!

thanx

[acoder]

Just compare the responseText with wherever the content is output, or change your PHP code to output something else when (no) changes have been made.

[canabatz]

how can i compare the response ,this is my problem ,i don't know how the pass the value from the php file ,how to get the right value to the ajax and compare the changes?

need little more help on that!!

thanx

[acoder]

The output from the PHP file will be in req.responseTex t as a string. You can simply compare against whatever value you've already set:

if (req.responseText == "...") {

[canabatz]

ok , im realy confused by this ajax and php thing ,i wan to make it short ,and i hope you can explain for me better!!

i got for example those two files

ajax.php

<?php 
echo "10";
?>

and ajax.js

function MakeRequest()
{
  var xmlHttp = getXMLHttp();
 
  xmlHttp.onreadystatechange = function()
  {
    if(xmlHttp.readyState == 4)
    {
      HandleResponse(xmlHttp.responseText);
    }
  }
 
  xmlHttp.open("GET", "ajax.php", true); 
  xmlHttp.send(null);
}
 
function HandleResponse(response)
{
  document.getElementById('ResponseDiv').innerHTML = response;
}
 

my quastion is , after i excute this script and the response is showing me "10" ,if after i change the php file to "11" or any thing else ,does the ajax will execute another function() if it sees that there is a change in the php file?

this is how i want it to be :

ajax is checking a php file for changes ,and if is is changed execute another function!!

thanx

[acoder]

In HandleResponse( ), document.getEle mentById('Respo nseDiv').innerH TML contains the old value and response contains the new value, so compare them:

if (document.getElementById('ResponseDiv').innerHTML == response) {
    // value hasn't changed...
} else {
    // value has changed...
}

[canabatz]

is this correct?

function MakeRequest()
{
  var xmlHttp = getXMLHttp();
 
  xmlHttp.onreadystatechange = function()
  {
    if(xmlHttp.readyState == 4)
    {
      HandleResponse(xmlHttp.responseText);
    }
  }
 
  xmlHttp.open("GET", "ajax.php", true); 
  xmlHttp.send(null);
 
  setTimeout('MakeRequest()', 4000);
}
 
 
 
 
 
 
function HandleResponse(response)
{
 
  if (document.getElementById('ResponseDiv').innerHTML == response) 
  {
 
   alert ("something changed");
 
  } 
 
   else 
 
  {
 
   alert ("nothing changed");
 
  }
 
 
}

[acoder]

It would be except that the Response Div must be set first in another request or during page load.

[canabatz]

can you please please correct my wrongs, im geting crazy !!

[acoder]

What's the ResponseDiv div initially set to?