SOLVED! Now I'm using the "Javascript Tag" Invocation Code (instead of Asynchronous Javascript Tag) serving Responsive and Centered image.
Just put the invocation code inside a DIV and added a piece of code in the end only for the addClass purpose, THIS WAY:
<div class="mydiv">
//INVOCATION CODE (I added "async" inside script tag hoping it to work asyncly, despit not being the Async invocation code)
<!-- Revive Adserver Javascript Tag - Generated with Revive Adserver v4.1.0-rc1 -->
<script async type='text/javascript'><!--//<![CDATA[
var m3_u = (location.protocol=='https:'?'https://example.com.br/adserver/www/delivery/ajs.php':'http://example.com.br/adserver/www/delivery/ajs.php');
var m3_r = Math.floor(Math.random()*99999999999);
if (!document.MAX_used) document.MAX_used = ',';
document.write ("<scr"+"ipt type='text/javascript' src='"+m3_u);
document.write ("?zoneid=1");
document.write ('&cb=' + m3_r);
if (document.MAX_used != ',') document.write ("&exclude=" + document.MAX_used);
document.write (document.charset ? '&charset='+document.charset : (document.characterSet ? '&charset='+document.characterSet : ''));
document.write ("&loc=" + escape(window.location));
if (document.referrer) document.write ("&referer=" + escape(document.referrer));
if (document.context) document.write ("&context=" + escape(document.context));
if (document.mmm_fo) document.write ("&mmm_fo=1");
document.write ("'><\/scr"+"ipt>");
//HERE IS THE SIMPLE CODE to add two Bootstrap classes on the image: make image Responsive and horizontally Centered.
$(document).ready(function () {
var img = $('.mydiv').contents().find('img').addClass('img-responsive center-block');
}); //END
//]]>--></script><noscript><a href='http://example.com.br/adserver/www/delivery/ck.php?n=a1389b42&cb=INSERT_RANDOM_NUMBER_HERE' target='_blank'><img src='http://example.com.br/adserver/www/delivery/avw.php?zoneid=1&cb=INSERT_RANDOM_NUMBER_HERE&n=a1389b42' border='0' alt='' /></a></noscript>
</div>
ericleonardo got a reaction from andrewatfornax in How to add a Class to IMG tag on image banner?