When user click link send it to one of X random Y

randomMe.html

<!-- Add this where you want your link, if you already have a element or button you would like to use, just add  onClick="randomMe"  to the element code, see example --> 
<a onClick="randomMe()" rel="nofollow" href="#">Link do ankiety</a>

<!-- Add this script anywhere on page, it will exectue when user click link / element and will give user a random number between 1 and 100 where we send all with 50 or less to one url and the others with more then 50 to the other one, that should give us a likley 50/50 splitt over time -->
<script>
function randomMe() {
  // Generate a number between 1 and 100
  var myNumber = Math.floor((Math.random() * 100) + 1);
  // If number is over 50..
  if (myNumber > 50) {
    // Add first url
    location.href = "https://ankiety.kozminski.edu.pl/index.php/844712/lang-pl";
  // If number is 50 or less..  
  } else {
    // Add second url 
    location.href = "https://ankiety.kozminski.edu.pl/index.php/126449/lang-pl";
  }
}
</script>