A tiny object that can return random numbers with different biases

WeightedRandom.js

// Demo / visualisation:
// https://codepen.io/EightArmsHQ/pen/BaavyPQ

let WeightedRandom = {
  random(){
    return Math.random();
  },
  sphere(){
    return (Math.sin(1-Math.random() * 2 * Math.PI)+1) / 2;
  },
  gradient(){
    return Math.tan(Math.random()-1.22) / 2.4 + 1.1;
  },
  reverseGradient(){
    return 1 - (Math.tan(Math.random()-1.22) / 2.4 + 1.1);
  },
  fire(){
    return Math.pow(Math.random(), 0.2);
  },
  reverseFire(){
    return 1 - (Math.pow(Math.random(), 0.2));
  },
  exponential(){
    return Math.pow((Math.random()), 10);
  },
  reverseExponential(){
    return 1 - (Math.pow((Math.random()), 10));
  },
  yesNo(){
    return Math.random() > 0.5 ? 1 : 0;
  },
  stepped(amount){
    // You should pass in amount, this is just for the demo
    amount = amount || 0.2;
    return Math.round(Math.random() / amount) * amount;
  }
}