added solution supporting Number.MAX_SAFE_INTEGER

[cameroncooper]

No description provided.

[cameroncooper]

modulo is not as fast as bitshifting, but is still fast

bitshift x 62,655,640 ops/sec ±0.95% (83 runs sampled)
modulo x 34,084,258 ops/sec ±0.96% (87 runs sampled)
Math.floor x 14,786,517 ops/sec ±2.06% (81 runs sampled)
parseInt x 14,127,969 ops/sec ±0.66% (88 runs sampled)
Fastest is bitshift

[tjmehta]

what about adding additional equality checks:

return (x >> 0 === x && x >> 0 > 0) || x === Number.MAX_VALUE || x === Number.MAX_SAFE_INTEGER

[fearphage]

FYI, all the tests are synchronous and don't need to use the done callback.