Basically Adblocker is used to hide the ads in the website.
We can find adblocker existed / installed or not by using javascript.
Below is the code for detect adblocker in browser by using javascript.
window.onload = function() {
setTimeout(function() {
if (typeof(window.google_jobrunner) === "undefined") {
alert("adblocker is existed");
}else{
alert("no adblocker found.");
}
}, 3000);
};