Weighted Random Number Generator

random.js

//http://stackoverflow.com/questions/30492259/get-a-random-number-focused-on-center
// max is non-inclusive
// bellFactor = 1 is normal flat RNG
// bellFactor = 2 is sawtooth shaped
// bellFactor = 4 is basic bell curve
function weightedRandom(max, bellFactor) {
    max = parseInt(max, 10);	
    bellFactor = parseInt(bellFactor || 1, 10);
    if (bellFactor < 1) {
    	bellFactor = 1;
    }
    
    var num = 0;
    for (var i = 0; i < bellFactor; i++) {
        num += Math.random() * (max/bellFactor);
    }    
    return Math.floor(num);
}