The code presented in this page can be used to detect if the visitor has an Ad-Blocker that blocks Ads, and to display a friendly message to visitor when the JavaScript is disabled or Ads are blocked.
The script was tested with Adblock Plus.

- Just add the following HTML /CSS /JS code in the pages of your website.
<div id='jsad_notify'>
Parts of this site works with JavaScript enabled; and without AdBlock.<br>
Please consider supporting us by disabling your Ad-Blocker on this website.
</div>

<style>
#jsad_notify{
background:#f8f800;
border:2px solid #0000be;
color:#ee0000;
font-size:20px;
font-weight:700;
margin:0;
padding:2px;
position:fixed;
top:40px;left:1%;right:1%;
text-align:center;
max-width:98vw;
}
</style>

<script>
// <![CDATA[
//if JavaScript enabled, it hides #jsad_notify
var jsad_notify = document.querySelector('#jsad_notify');
jsad_notify.style.display ='none';

//adds a child-element in page which usually is blocked by Ad-Blocker
var test_adb = document.createElement('div');
test_adb.innerHTML ='&nbsp;';
test_adb.className ='adsbox';
document.body.appendChild(test_adb);
window.setTimeout(function(){
 //if Ads blocked it shows the message, else it removes the #jsad_notify
 if(test_adb.offsetHeight ===0) jsad_notify.style.display ='block';
 else jsad_notify.outerHTML ='';

 document.body.removeChild(test_adb); //removes test_adb elm.
}, 700);
// ]]>
</script>
- To change the position and design of the message, edit the CSS properties of the #jsad_notify element.

Daily Test with Code Example

HTML
CSS
JavaScript
PHP-MySQL
Which HTML5 tag defines marked text? (can be used to highlight parts of text)
<mark> <embed> <span>
<p>Free corses: <mark>coursesweb.net</mark> for Web Development.</p>
Which CSS pseudo-class adds a style to an element when the mouse is over it?
:focus :hover :active
a:hover {
  font-weight: bold;
  color: #00da01;
}
Click on the function which returns a string value that represents the number rounded to the x digits after the decimal point.
toPrecision(x) toFixed(x) floor(x)
var num = 12.34567;
num = num.toFixed(2);
alert(num);       // 12.35
Indicate the PHP function which reads an entire file into an array.
[) file() readfile()
$arr = file("a_file.txt", FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES);
var_export($arr);
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