Is it possible to change a Javascript Variable from an Ajax Response?

Question

I'm trying to update a Javascript variable that controls a scrolling script based upon some Ajax code. The Ajax code is supposed to add to the JS Var when conditions are true in the Ajax script. Is there any way to trigger this?

Thanks!

edit: I'm not sure how to change the value of the variable. I've tried changing it via the Ajax but it doesn't get parsed. I've also tried using PHP inside of JS to check a condition, but doing that only works once.

JS Code

function speedUp()
    {
    actualheight = actualheight + 50;
    }

function slowDown()
{
actualheight = actualheight - 50;
}

function ajaxFunction()
{
var xmlhttp = createRequestObject();
xmlhttp.onreadystatechange=function()
{
if(xmlhttp.readyState==4)
  {
   document.getElementById('iemarquee').innerHTML=xmlhttp.responseText;
   document.getElementById('iemarquee2').innerHTML=xmlhttp.responseText;
  }
}
xmlhttp.open("GET","saleCallTest.php",true);
xmlhttp.send(null);
}

/*
Cross browser Marquee II- © Dynamic Drive (www.dynamicdrive.com)
For full source code, 100's more DHTML scripts, and TOS, visit http://www.dynamicdrive.com
Modified by jscheuer1 for continuous content. Credit MUST stay intact for use
*/

//Specify the marquee's width (in pixels)
var marqueewidth="500px"
//Specify the marquee's height
var marqueeheight="500px"
//Specify the marquee's marquee speed (larger is faster 1-10)
var marqueespeed=1
//Specify initial pause before scrolling in milliseconds
var initPause=1000
//Specify start with Full(1)or Empty(0) Marquee
var full=1
//Pause marquee onMousever (0=no. 1=yes)?
var pauseit=0
//Specify Break characters for IE as the two iterations
//of the marquee, if text, will be too close together in IE
var iebreak='<p></p>'

//Specify the marquee's content
//Keep all content on ONE line, and backslash any single quotations (ie: that\'s great):

var marqueecontent='<?php for($i=0;$i<=count($saleItems);$i++)
{
if ($saleItems[$i]['stateOfItem'] =="Sold" || $saleItems[$i]['stateOfItem'] =="Unsold")
{
$_SESSION['countItems']++;

echo $saleItems[$i]['itemNumber'];
echo $saleItems[$i]['stateOfItem'] . '<br />';

}};
?>'


////NO NEED TO EDIT BELOW THIS LINE////////////
var copyspeed=marqueespeed
var pausespeed=(pauseit==0)? copyspeed: 0
var iedom=document.all||document.getElementById
var actualheight=''
var cross_marquee, cross_marquee2, ns_marquee

function populate(){
if (iedom){
var lb=document.getElementById&&!document.all? '' : iebreak
cross_marquee=document.getElementById? document.getElementById("iemarquee") : document.all.iemarquee
cross_marquee2=document.getElementById? document.getElementById("iemarquee2") : document.all.iemarquee2
cross_marquee.style.top=(full==1)? '8px' : parseInt(marqueeheight)+8+"px"
cross_marquee2.innerHTML=cross_marquee.innerHTML=marqueecontent+lb
actualheight=cross_marquee.offsetHeight
cross_marquee2.style.top=(parseInt(cross_marquee.style.top)+actualheight+8)+"px" //indicates following #1

}
else if (document.layers){
ns_marquee=document.ns_marquee.document.ns_marquee2
ns_marquee.top=parseInt(marqueeheight)+8
ns_marquee.document.write(marqueecontent)
ns_marquee.document.close()
actualheight=ns_marquee.document.height

}
setTimeout('lefttime=setInterval("scrollmarquee()",20)',initPause)
}
window.onload=populate

function scrollmarquee(){

if (iedom){
if (parseInt(cross_marquee.style.top)<(actualheight*(-1)+8))
cross_marquee.style.top=(parseInt(cross_marquee2.style.top)+actualheight+8)+"px"
if (parseInt(cross_marquee2.style.top)<(actualheight*(-1)+8))
cross_marquee2.style.top=(parseInt(cross_marquee.style.top)+actualheight+8)+"px"
cross_marquee2.style.top=parseInt(cross_marquee2.style.top)-copyspeed+"px"
cross_marquee.style.top=parseInt(cross_marquee.style.top)-copyspeed+"px"
}

else if (document.layers){
if (ns_marquee.top>(actualheight*(-1)+8))
ns_marquee.top-=copyspeed
else
ns_marquee.top=parseInt(marqueeheight)+8
}
}

if (iedom||document.layers){
with (document){
if (iedom){
write('<div style="position:relative;width:'+marqueewidth+';height:'+marqueeheight+';overflow:hidden" onMouseover="copyspeed=pausespeed" onMouseout="copyspeed=marqueespeed">')
write('<div id="iemarquee" style="position:absolute;left:0px;top:0px;width:100%;background:black;color:white;font-size:30pt;">')
write('</div><div id="iemarquee2" style="position:absolute;left:0px;top:0px;width:100%;z-index:100;background:black;color:white;font-size:30pt;">')
write('</div></div>')

}
else if (document.layers){
write('<ilayer width='+marqueewidth+' height='+marqueeheight+' name="ns_marquee">')
write('<layer name="ns_marquee2" width='+marqueewidth+' height='+marqueeheight+' left=0 top=0 onMouseover="copyspeed=pausespeed" onMouseout="copyspeed=marqueespeed"></layer>')
write('</ilayer>')
}
}
}


</script>

AJAX->PHP CODE

<?php
session_start();

//NuSoap Library
require_once('./lib/nusoap.php');
$_SESSION['countTotal'] = 0;

//Creating a Client
$client = new nusoap_client('http://xx.xx.x.xxx:xxxx/WSSERVICE/services/SERVICE?WSDL');



$saleItems= $client->call("getItems", array("Sale" => '001'));

$_SESSION['countNew'] = 0;


$countPresale = count($saleItems);
$timer = $countPresale * 3.15;

 for($i=0;$i<=count($saleItems);$i++)
{
if ($saleItems[$i]['stateOfItem'] =="Sold" || $saleItems[$i]['stateOfItem'] =="Unsold")
{
$_SESSION['countNew']++;

echo $saleItems[$i]['itemNumber'];
echo $saleItems[$i]['stateOfItem'] . '<br />';

}};

if($_SESSION['countNew'] < $_SESSION['countVehicles'])
{
$_SESSION['countTotal']--;
}

if($_SESSION['countNew'] > $_SESSION['countVehicles'])
{
$_SESSION['countTotal']++;
}


if($_SESSION['countTotal'] < 0)
{
$opx = 3 * ($_SESSION['countItems'] - $_SESSION['countNew']);
echo 'actualheight = parseInt(actualheight) + parseInt(' . $opx . ');';
$_SESSION['countVehicles'] = $_SESSION['countNew'];

}

if($_SESSION['countTotal'] > 0)
{
$opx = 3 * ($_SESSION['countItems'] + ($_SESSION['countNew'] - $_SESSION['countNew']));
echo 'actualheight = parseInt(actualheight) - parseInt(' . $opx . ');';
$_SESSION['countItems'] = $_SESSION['countNew'];

}



?>

Answer 1

Assuming that the variable is not locked away in a different namespace with no interface made available, then of course.

"Ajax" just means "Fetch some data from the server using JS without leaving the page, then run some JS".

There is nothing special that adds extra limitations to what that JS can do.

Answer 2

I ran into some issues with this as well. Probably namespace problems like another answer here suggests.
Rather than figure out the what/when/why, I just used <input name="blah" type=hidden> and then update that and read that with Javascript:

Then, to write the variable:document.getElementById('blah').value='some new value';

To read the variable: somevar=document.getElementById('blah').value;

That has worked every time. Actually figuring out the correct namespace would be a better option, but this works.

EDIT: Are you using any Javascript libraries to do your ajax for you, or just coding it from scratch? I've used xajax, Prototype, and Jquery for things like this. Jquery is my new baby, but 5 years ago already this was dead simple in xajax.

I'm not sure I want to steer you down that path but for a php programmer, xajax is a pretty simple method to learn. Jquery is more powerful and extensible though in my opinion.

EDIT2: Far as I can tell you are returning both HTML and javascript to be executed in the same response. Including a javascript in your response doesn't make it get executed. Perhaps you should be serializing your return with JSON so you can eval your javascript to be executed, and assign your innerHTML separately. Just for reference, the same thing you could do in xajax with just:

$objResponse->addAssign("idhere","innerHTML", "some html");
$objResponse->addScript("somvar = somevar + someothervar");