Keep Ajax alive - php

Question

I'm trying to get my ajax to request information from the server and also keep it alive for at least 1 minuite before having a break and restarting and getting and passing a new streamitem_id if their were one inserted since the last call.
Currently it runs so fast and only once and I don't understand why.
AJAX
<script type="text/javascript" charset="utf-8">
function wait() {
var streamitem_id =<? echo $streamitem_catch['streamitem_id']; ?>;
$.ajax({
type: "POST",
url: "testingajaxfeed.php?streamitem_id=" + streamitem_id,
async: true,
cache: false,,
dataType: "json",
data: {streamitem_id: streamitem_id},
success: function (response) {
setTimeout("wait()",1000);
$("#homestatusid").prepend("MY INSERTED RESPONSE");
},
});
}
$(document).ready(function(){
wait();
});
</script>
PHP
if (isset($_POST['streamitem_id'])) {
$lastID = (int)$_POST['streamitem_id'];
if(empty($lastID)) {
die('timeout');
}
else {
$following_string = $_SESSION['id'];
$result="SELECT d.*, c.*, u.*
FROM streamdata AS d
JOIN streamdata_comments AS c ON d.streamitem_id = c.comment_streamitem
JOIN users AS u ON u.id = c.comment_poster
WHERE d.streamitem_id > '$lastID'
AND c.comment_poster = '$following_string'
AND (d.streamitem_creator = '$following_string')
OR d.streamitem_creator IN $friendlist
AND d.streamitem_type_id NOT IN ('3')
ORDER BY '$lastID' DESC LIMIT 1";
$result = mysqli_query($mysqli, $result) or die(mysqli_error($mysqli));
while ($resultArr = mysqli_fetch_array($result)) {
$json = array();
$json['streamitem_id'] = $resultArr['streamitem_id'];
$json['streamitem_content'] = $resultArr['streamitem_content'];
$json['streamitem_timestamp'] = Agotime($resultArr['streamitem_timestamp']);
$json['comment_id'] = $resultArr['comment_id'];
$json['comment_content'] = $resultArr['comment_content'];
$json['comment_poster'] = $resultArr['comment_poster'];
$json['comment_datetime'] = Agotime($resultArr['comment_datetime']);
$json['comment_streamitem'] = $resultArr['comment_streamitem'];
$json['username'] = $resultArr['username'];
$json['id'] = $resultArr['id'];
$json['first'] = $resultArr['first'];
$json['middle'] = $resultArr['middle'];
$json['last'] = $resultArr['last'];
echo json_encode($json);
}}}

Answer 1

setTimeout does not work like you expect. An ajax-request can't be "kept alive" like you want. The request is sent, the PHP-script returns the content and the ajax-script get's the result. All this happens within ~1-2 seconds.
If this is used for some sort of stream (as it looks like), you would have to make the function repeat itself again and again over a small interval.
I've changed your code like this:
<script type="text/javascript" charset="utf-8">
function wait() {
var streamitem_id =<? echo $streamitem_catch['streamitem_id']; ?>;
$.ajax({
type: "POST",
url: "testingajaxfeed.php?streamitem_id=" + streamitem_id,
async: true,
cache: false,
dataType: "json",
data: {streamitem_id: streamitem_id},
success: function (response) {
$("#homestatusid").prepend("MY INSERTED RESPONSE");
},
});
}
$(document).ready(function(){
setInterval(wait,10000);
});
</script>
The ajax-script will fire every 10 seconds. You can edit the speed yourself, but keep in mind that too many requests in a short timeperiod can make your server crash/go slow.

Answer 2

In your PHP script, you'll need to use the sleep function in order to keep your connection alive.
Something like:
function callScript(callback) {
$.post('myscript.php',{data:data},function(data) {
if (data == -1) {
return callScript(callback);
}
return callback(data);
}
}
myscript.php
$interval = 50;
$iters = floor(1000 / $interval);
while($conditional === false) {
if (--$iters < 1) { die(-1); }
sleep($interval);
}
echo $json;
While this isn't exactly what you need, it can easily be adapted to what you need. I've done this with other stuff, while costly, you can use a sql statements to wait for entries to be added etc.