Approximation to normal distribution by summing three uniformly distributed random numbers, normalized to [-1,1].

approximatenormal.js

function rnd_snd() {
	return (Math.random()*2-1)+(Math.random()*2-1)+(Math.random()*2-1);
}

function rnd(mean, stdev) {
	return Math.round(rnd_snd()*stdev+mean);
}