Number.sign() in javascript

Question

Wonder if there are any nontrivial ways of finding number\'s sign (signum function)?
May be shorter / faster / more elegant solutions than the obvious one

Answer 1

Very similar to Martijn's answer is

function sgn(x) {
    isNaN(x) ? NaN : (x === 0 ? x : (x < 0 ? -1 : 1));
}

I find it more readable. Also (or, depending on your point of view, however), it also groks things that can be interpreted as a number; e.g., it returns -1 when presented with '-5'.