var onmessage = function(event) { postMessage({"n" : event.data.n, "factors" : factor(event.data.n), "id" : event.data.id}); }; function factor(n) { var factors = []; for(p = 2; p <= n; p++) { if((n % p) == 0) { factors[factors.length] = p; n /= p; } } return factors; }