JS function that replaces in-between characters with stars

email-with-stars.js

function hiddenEmailAddress(email) {
  var emailLength = email.length;
  var atPosition = email.search('@');
  var unhiddenPortion = email.slice(atPosition, emailLength);

  var i;
  var hiddenEmail = '';
  for(i = 0; i < atPosition; i++) {
    if(i === 0 || i === atPosition - 1) {
        hiddenEmail += email[i];
      } else {
        hiddenEmail += email[i].replace(email[i], '*');
      }
  }

  hiddenEmail += unhiddenPortion;
  return hiddenEmail;
}

hiddenEmailAddress('[email protected]');
// a*******[email protected]'