var expression = /(https?:\/\/(?:www\.|(?!www))[a-zA-Z0-9][a-zA-Z0-9-]+[a-zA-Z0-9]\.[^\s]{2,}|www\.[a-zA-Z0-9][a-zA-Z0-9-]+[a-zA-Z0-9]\.[^\s]{2,}|https?:\/\/(?:www\.|(?!www))[a-zA-Z0-9]+\.[^\s]{2,}|www\.[a-zA-Z0-9]+\.[^\s]{2,})/gi;
var regex = new RegExp(expression);
var check = [
'http://www.foufos.gr',
'https://www.foufos.gr',
'http://foufos.gr',
'http://www.foufos.gr/kino',
'http://werer.gr',
'www.foufos.gr',
'www.mp3.com',
'www.t.co',
'http://t.co',
'http://www.t.co',
'https://www.t.co',
'www.aa.com',
'http://aa.com',
'http://www.aa.com',
'https://www.aa.com',
'www.foufos',
'www.foufos-.gr',
'www.-foufos.gr',
'foufos.gr',
'http://www.foufos',
'http://foufos',
'www.mp3#.com'
];
check.forEach(function(entry) {
if (entry.match(regex)) {
$("#output").append( "<div >Success: " + entry + "</div>" );
} else {
$("#output").append( "<div>Fail: " + entry + "</div>" );
}
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div id="output"></div>