protect_email = function (user_email) {  
    var avg, splitted, part1, part2;  
    splitted = user_email.split("@");  
    part1 = splitted[0];  
    avg = part1.length / 2;  
    part1 = part1.substring(0, (part1.length - avg));  
    part2 = splitted[1];  
    return part1 + "...@" + part2;  
};  
  
console.log(protect_email("robin_singh@example.com"));