Write a function to get prime numbers upto n.(JS) follow up question: Improve its performance and efficiency.
Sigiloso
function findPrimUpTo(n){ var primes = []; for(var i=3; i<=n; i+=2){ if(primes.every(function(prime){ return i%prime !==0})){ primes.push(i); } } primes.unshift(2); return primes; }