Organism.js

class Organism {
  constructor(r, g, b) {
    this.r = r;
    this.g = g;
    this.b = b;
    this.mutationSize = 10; //Must be greater than 2
  }
  reproduce() {
    // Prevents negative numbers from appearing
    let newR = Math.max(this.r + this.mutateTrait(), 0);
    let newG = Math.max(this.g + this.mutateTrait(), 0);
    let newB = Math.max(this.b + this.mutateTrait(), 0);
    return new Organism(newR, newG, newB);
  }

  mutateTrait() {
    let multiplier = Math.random() - 0.5;
    if(multiplier < 0) {
      return randomValue(this.mutationSize) * -1;
    } else {
      return randomValue(this.mutationSize);
    }
  }
}

function randomValue(range) {
  return Math.floor(Math.random() * range);
}