Protected Email - 1 or 2?

Question

//Code one
function protectedEmail(email) {
var hiddenChars, hideEmail, j;
for(let i = 0; i < email.length; i++) {
if(email[i] == "@") {
j = i;
}
}
hiddenChars = email.slice(4, j);
hideEmail = email.replace(hiddenChars, "...");
return hideEmail;
}

//Code two
protected_email = function(user_email) {
var avg, splitted, part1, part2;
splitted = user_email.split("@");
part1 = splitted[0];
avg = part1.length / 2;
part1 = part1.substring(0, (part.length - avg);
part2 = splitted[1];
return part1 + "...@" + part2;
}

The code hides your email in this format "[e-mail] outputs [e-mail]".
Which code is more efficient or better written, Code one or Code two?

Answer 1

According to performance.now() both are almost equally efficient

Answer 2

RDC What is performance.now()?

Answer 3

https://developer.mozilla.org/en-US/docs/Web/API/Performance/now