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Function call not returning control AJAX - PHP - MYSQLI

I have checked all the similar questions to this but not found anything that helped... so here goes!
I am writing designing a site for my college project. It simply is an image gallery. I have a counter displayed for each image that increments each time the image is clicked. When the page refreshes the new number is displayed. With me so far?
The problem is that after the database update is completed the return does not complete the rest of the code...
echo "<div class='gridImg'><a href=".$imgpath." data-lightbox='countryside' data-title='".$row['ldesc']."' onclick='"."showUser(&#39".$fname."&#39)'>";
The above line is in a php file and the function in question is showUser, which passes a variable $fname...
function showUser(str) {
if (str === "") {
document.getElementById("txtHint").innerHTML = "";
return;
} else {
if (window.XMLHttpRequest) {
xmlhttp = new XMLHttpRequest();
}
xmlhttp.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 200) {
document.getElementById("txtHint").innerHTML =
this.responseText;
}
};
xmlhttp.open("GET","../php/countrysideupdateviews.php?q="+str,true);
xmlhttp.send();
return;
}
}
The above script takes the passed value and hands it over to countrysideupdateviews.php (Sorry if this script is a mess, I am new to AJAX and took it from the W3Schools site.
<?php
$q = $_GET['q'];
$conn=new mysqli('localhost','user','pass','dbname');
$sql="UPDATE countryside SET views = views + 1 WHERE fname = '".$q."'";
$result=$conn->query($sql);
mysqli_close($conn);
?>
The above php file updates the database.
Ok...
So, a user clicks on one of the images on-screen, which opens a lightbox gallery, BUT also updates the view count and then returns control - except that everything works - the update takes place - but the lightbox does not start, instead a static larger image of the one that was clicked is shown. The only way to clear it is to refresh the site, which does reflect the updated counter.
I have added returns to the onclick function call which does return control but the counter is not updated. Where am I going wrong? Bear in mind please I am still learning and I hope this makes sense :)

The argument to onclick must be a function. showUser("foo") is not a function. You're also missing event.preventDefault() which prevents the click action from opening the link.
Change your showUser to
function showUser(str) {
return function(event) {
if (str === "") {
document.getElementById("txtHint").innerHTML = "";
} else {
if (window.XMLHttpRequest) {
var xmlhttp = new XMLHttpRequest();
}
xmlhttp.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 200) {
document.getElementById("txtHint").innerHTML = this.responseText;
}
};
xmlhttp.open("GET","../php/countrysideupdateviews.php?q="+str,true);
xmlhttp.send();
}
event.preventDefault();
};
}

Ok, after playing around with #apaatsio's answer I got it working, this is what the function now looks like...
function showUser(str) {
if (str === "") {
document.getElementById("txtHint").innerHTML = "";
return;
} else {
if (window.XMLHttpRequest) {
// code for IE7+, Firefox, Chrome, Opera, Safari
xmlhttp = new XMLHttpRequest();
}
xmlhttp.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 200) {
document.getElementById("txtHint").innerHTML = this.responseText;
}
};
xmlhttp.open("GET","../php/countrysideupdateviews.php?q="+str,true);
xmlhttp.send();
event.preventDefault();
}
}
It looks like preventing the click opening the link worked just fine - thanks :)

How to stream new data to clients browser when index.html change, without the need of refreshing or reloading the web page

I am new on Html. What i need is this.
I have an index.html file on a server which is blank.
I open it and write some text inside the body all the time.
What i want is that when i save the html,
the new data to appear on my clients browser
without the need to refresh or reload the page.
I have no idea on how to do it,so i haven't try anything.
Is it possible? Is it simple?

This is a sample javascript code to read an online url and update the content container with the result.
I couldn't find a simple live update page so used my own website readme in github...
var timeout = 2000,
index = 1,
cancel = false,
url = 'https://raw.githubusercontent.com/petjofi/krivoshiev.com/master/README.md';
function update() {
updateIndex();
load(url, done);
if (!cancel) setTimeout(update, timeout);
}
function updateIndex() {
document.getElementById("index").innerHTML = index++;
}
function done(result) {
document.getElementById("content").innerHTML = result;
}
function load(url, callback) {
var xmlHttp = new XMLHttpRequest();
xmlHttp.onreadystatechange = function() {
if (xmlHttp.readyState == 4 && xmlHttp.status == 200)
callback(xmlHttp.responseText);
}
xmlHttp.open("GET", url, true); // true for asynchronous
xmlHttp.send(null);
}
<button onclick="update()">start</button>
<button onclick="cancel=true">stop</button>
<span>updating: <span id="index">0</span></span>
<div style="margin-top: 20px" id="content"></div>

jQuery - load data to variable, check data and update in DIV

I make very, very simple intranet chat. I load every 2 sec data from URL to DIV. But I want (and I don't know how) load data to variable, compare data from DIV and if !=, update in DIV. And scroll to down "page" in this DIV. Please, help me stackoverflowers! :)
var chatInterval;
function chatLoad(){
chatInterval = setInterval(function(){
$('#chat-conversations').load('/AJAX/Chat.app');
}, 2000);
}

Instead of just loading it directly put it on a variable first and compare it. That's why I use .get instead of .load, .load loads the content directly into the element.
var chatInterval;
var chatContent = "";
function chatLoad(){
chatInterval = setInterval(function(){
$.get('/AJAX/Chat.app',function(data){
if(data!=chatContent){
$('#chat-conversations').html(data);
chatContent = data;
}
})
}, 2000);
}

First of all you must understand that compare all data is bad idea, you just need check that user have new messages whatever.
Also you must now about long polling and short polling good explanation.
Why its bad idea to compare all data?
Because after a 5 minutes you will receive a BIG BIG bunch of data (performance).
Hor compare if you want:
var _current_data = null;
var interval = setInterval(function(){
// your logic to receive data, we receive response from server
if(!_current_data) _current_data = response;
else if(_current_data != response){
// Render logic (insert data into html tags and return html as string)
$("div").html(render(current_data));
}
}, 2000);

You can use ajax to get the latest posts without reloading the page as you said with the interval of 2 second.
function getXmlHttpRequest() {
var xmlhttp;
if (window.XMLHttpRequest) {
xmlhttp = new XMLHttpRequest();
// code for IE7+, Firefox, Chrome, Opera, Safari
}
else if (window.ActiveXObject) {
xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
// code for IE5 and IE6
}
else {
alert("Browser doesn't support Ajax..!!");
}
return xmlhttp;
}
function loadData() {
xmlhttp = getXmlHttpRequest();
if (xmlhttp !== null) {
xmlhttp.onreadystatechange = function() {
if (xmlhttp.readyState < 4) {
document.getElementById('your-div').innerHTML = "<img src = 'loader-animation.gif'/>";
}
else if (xmlhttp.readyState === 4) {
var res = xmlhttp.responseText;
if (res.trim() !== "error") {
document.getElementById('your-div').innerHTML = res;
} else {
document.getElementById('your-div').innerHTML = "<img src = 'error.png' style='vertical-align:middle;'/>";
}
}
}
xmlhttp.open("POST", "data_loading_page.php", true);
xmlhttp.send(null);
}
}
on data_loading_page.php (any media of you use php or jsp or anything) print your posts using a while. so whenever the function calls the php page then you'll get the updates;
call the script by
setInterval(function() {
loadData();
}, 2000);

Turning an OnClick Event Into A Timed Event with JavaScript & AJAX

Im currently in the learning process with AJAX & JavaScript..
I have a quick question to the wise..
How can i turn the code below into a timed event instead of an OnClick event.
**For Example i would like to refresh the "showlist" DIV every 5 seconds...
I understand that this is working code and goes against the rules of the site but if i were to post my non working code it would just confuse things as it has me..
I am trying to slowly understand the basics :)
Any guidance would be greatly appreciated
<!DOCTYPE html>
<html>
<head>
<script>
function loadXMLDoc()
{
var xmlhttp;
if (window.XMLHttpRequest)
{
xmlhttp=new XMLHttpRequest();
}
else
{
xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
}
xmlhttp.onreadystatechange=function()
{
if (xmlhttp.readyState==4 && xmlhttp.status==200)
{
document.getElementById("showlist").innerHTML=xmlhttp.responseText;
}
}
xmlhttp.open("GET","playlist.php?t=" + Math.random(),true);
xmlhttp.send();
}
</script>
</head>
<body>
<h2>Ajax Testing...</h2>
<button type="button" onclick="loadXMLDoc()">Request data</button>
<div id="showlist"></div>
</body>
</html>

You can change loadXMLDoc function to make use of setTimeout. Consider this example:
function loadXMLDoc() {
var xmlhttp,
timer;
if (window.XMLHttpRequest) {
xmlhttp = new XMLHttpRequest();
} else {
xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
}
xmlhttp.onreadystatechange = function () {
if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
document.getElementById("showlist").innerHTML = xmlhttp.responseText;
}
};
xmlhttp.onerror = function() {
clearTimeout(timer);
};
xmlhttp.open("GET", "playlist.php?t=" + Math.random(), true);
xmlhttp.send();
timer = setTimeout(loadXMLDoc, 5000);
}
Function issues AJAX request and set up a 5s timeout. I also added basic onerror callback to clear timer just in case.

I once made a kind of tv, which automatically changed the 'screen' after 3 seconds.
Maybe you can re-use my code?
// This is the div called myScreen
var myScreen = document.getElementById('myScreen');
// This is an array, which is holding the names of the pictures
var myPics = ['img-screen1.png','img-screen2.png'];
// This is looking at how many things the array holds
var totalPics = myPics.length;
// Now this is where the magic begins, this keeps looping around and around, and
// makes sure all the pictures are being showed, one by one.
var i = 0
function loop() {
if(i > (totalPics - 1)){
i = 0;
}
myScreen.innerHTML = '<img src="images/'+myPics[i]+'">';
i++;
loopTimer = setTimeout('loop()',3000);
}
loop();
I hope you can re-use this for your project, and I hope you kind of understand what I mean, if I need to clarify, just ask me :).
So what you need to do, is refresh the array when you got new item in your showlist.

This function (if placed inside the same script tag after your loadXMLDoc fn) will execute and call your function and then itself again every 5 seconds (recursively). You could call setInterval instead, but that runs the risk of occasionally missing a cycle if the js engine is busy:
(function doMeSelf(){
setTimeout(function(){
loadXMLDoc();
doMeSelf();
},5000);
})();
Enclosing the function def inside parens, and then followed by () is called an immediately invoked function expression.
See this question for some background: What do parentheses surrounding a object/function/class declaration mean?

How make ajax update every (n) number of seconds with out using jquery but using javascript?

I'm trying to hava a javascript poll the server every (n) number of seconds how would I do this with javascript?

Assuming you are using jQuery:
var seconds = 5;
setInterval(function(){
$.ajax({
url: 'something.something',
data: 'something'
});
}, seconds * 1000)
Without jQuery:
var seconds = 5;
setInterval(function(){
some_ajax_function();
}, seconds * 1000)
Or as #Felix suggests below:
var seconds = 5;
some_ajax_function(seconds);
function some_ajax_function(seconds){
..ajax
onsuccess: setTimeout(function(){some_ajax_function(seconds);},
seconds * 1000)
}

It is simple with the following function
window.setInterval("yourfunctionWithAjaxRequestETC", time_in_ms);});
Enjoy :)

first, we need to make our ajax request object. We need to take different browsers into account.
var xmlhttp;
if (window.XMLHttpRequest)
{
// code for IE7+, Firefox, Chrome, Opera, Safari
xmlhttp=new XMLHttpRequest();
}
else
{
// code for IE6, IE5
xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
}
Now, we'll write our function to send a request
function askData(){
xmlhttp.open("GET","myinfosource.php",true); // opens a Get request to the url myinfosource.php, and sets the request to asynchronuous.
xmlhttp.send(); //sends the request
}
Now, let's write an event handler that changes the HTML when the info comes back.
xmlhttp.onreadystatechange=function()
{
if (xmlhttp.readyState==4 && xmlhttp.status==200) //if we reveived data (readystate 4 means that information was received. status 200 is the status of the HTTP request, where 200 means 'ok'.
{
//insert data into the div you want.
document.getElementById("myDiv").innerHTML=xmlhttp.responseText;
}
}
And finally, we set an interval on the first function we wrote to make it run every x seconds.
setInterval('askData',10000);
this will refresh your data.
I hope you see now why most people use a framework such as jquery to use AJAX. One of the major advantages of js frameworks is that they work around browser incompatibilities so that you, as the developer can concentrate on the task at hand.

I assume that there is a servlet with URL Pattern /UpdateCount is configured in web.xml to provide dynamic data/content and there is a div element countStatDiv in the jsp page.
The following code refreshes/updates the content of countStatDiv at every 30 seconds using GET method and variable seconds value can be changed according to the need:
<script>
var request;
var seconds=30;
function getRequestObject(){
setInterval(function() {sendRequest();},seconds*1000);
if (window.ActiveXObject){
return (new ActiveXObject("Microsoft.XMLHTTP"));
} else if (window.XMLHttpRequest){
return(new XMLHttpRequest());
} else {
return (null);
}
}
function sendRequest(){
request = getRequestObject();
request.onreadystatechange = handleResponse;
request.open("GET", "../UpdateCount", true);
request.send(null);
}
function handleResponse(){
if((request.readyState == 4)&&(request.status == 200)){
var serverResponse = request.responseText;
var statCtrl=document.getElementById("countStatDiv");
statCtrl.innerHTML=serverResponse;
}
}
</script>