function foo(date) { var F = date.split(" "); var D = F[0].split("-"); var C = F[1].split(":"); return new Date(D[0], D[1], D[2], C[0], C[1], C[2]); } function test() { with(this) {}; for (var i = 0; i < 1200; i++) foo("13-5-2015 18:30:" + i); } test();