Project Euler #10, ~850ms run time

10.js

var // Program setup
isPrime = require("./isprime"),
start = (new Date()).getTime(),
end;

var // Program specific
ceil = 2e6,
total = 2,
k = 3;


for ( ; k <= ceil; k++ ) {
  if ( isPrime(k) ) {
    total += k;
  }
}

end = (new Date()).getTime() - start;

console.log( (total === 142913828922 && "WIN") || "LOSE" );
console.log( end >= 1000 ? (end/1000) + "s" : end + "ms"  );

isprime.js

function isPrime( num ) {

  var sqrt = Math.sqrt( num ),
  i = 3;

  if ( num === 1 || (num > 2 && (num % 2) === 0) ) {
    return false;
  } else {
    for ( ; i <= sqrt; i = i + 2 ) {
      if ( num % i === 0 ) {
        return false;
      }
    }
  }

  return true;
}

console.assert( !isPrime(1) );
console.assert( isPrime(2) );
console.assert( isPrime(3) );
console.assert( isPrime(5) );
console.assert( !isPrime(4) );
console.assert( !isPrime(6) );



if ( typeof exports !== "undefined" ) {
  module.exports = isPrime;
}