Loading icon on ajax postback in PHP

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CSS

This is my first php project. I have imlemented partial ajax postback by referring to this article of PHP AJAX MYSQL from W3Schools

Now, I am trying to show a loading gif when the partial loading starts and hide it when the partial loading completes. Here is the code that I am using in Javascript:

<pre lang="Javascript">function showUser1(str) 
    {
        if (str == "") 
        {
            document.getElementById("mems").innerHTML = "I caanot fetch: " + str;
            return;
        }
        else 
        { 
            document.getElementById("loadgif").style.visibility= "visible";
            if (window.XMLHttpRequest) 
            {
                // code for IE7+, Firefox, Chrome, Opera, Safari
                xmlhttp = new XMLHttpRequest();
            }
            else 
            {
                // code for IE6, IE5
                xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
            }
            xmlhttp.onreadystatechange = function() 
            {
                if (xmlhttp.readyState == 4 && xmlhttp.status == 200) 
                {
                    document.getElementById("outerpicwrapper").innerHTML = "";
                    document.getElementById("mems").innerHTML = xmlhttp.responseText;
                }
            };
            xmlhttp.open("GET","getmembers.php?q2="+str,true);
            xmlhttp.send();
            document.getElementById("loadgif").style.visibility= "hidden";
        }
    }

In the first line of body, I have written:

HTML

<img id="loadgif" src="img/loading.gif"

class="loadinggif" />
In the CSS file, i have written:

CSS

.loadinggif
{
position: absolute;
z-index: 200;
visibility: hidden;
}

The code is working fine and shows the data but, loading gif is not shown. I have even tried display:none and display:block in place of visibility. Kindly help.

What I have tried:

visibility: hidden
display: none

Posted 1-Aug-16 21:36pm

Member 8057273

Updated 2-Aug-16 5:11am

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Richard Deeming · Answer 1 · 2016-08-02T05:11:00

You're hiding the element again before the request has completed. Move the visibility = "hidden" line inside the if block in the onreadystatechange callback:

JavaScript

xmlhttp.onreadystatechange = function() 
{
    if (xmlhttp.readyState == 4 && xmlhttp.status == 200) 
    {
        document.getElementById("outerpicwrapper").innerHTML = "";
        document.getElementById("mems").innerHTML = xmlhttp.responseText;
        
        // Add here:
        document.getElementById("loadgif").style.visibility= "hidden";
    }
};

xmlhttp.open("GET","getmembers.php?q2="+str,true);
xmlhttp.send();

// Remove here:
// document.getElementById("loadgif").style.visibility= "hidden";