Father & Son Analogy

father-and-son-inheritance.js

// https://alexsexton.com/blog/2013/04/understanding-javascript-inheritance/ 
// Let's take a set of 4 genes for ease of
// example here. We'll put them in charge
// a few things.
function Human (name, genes_mom, genes_dad) {
  this.name = name;

  // Set the genes
  this.genes = {
    darkHair: this._selectGenes(genes_mom.darkHair, genes_dad.darkHair),
    smart:    this._selectGenes(genes_mom.smart,    genes_dad.smart),
    athletic: this._selectGenes(genes_mom.athletic, genes_dad.athletic),
    tall:     this._selectGenes(genes_mom.tall,     genes_dad.tall)
  };

  // Since genes affect you since birth we can set these as actual attributes
  this.attributes = {
    darkHair: !!(~this.genes.darkHair.indexOf('D')),
    smart: !!(~this.genes.smart.indexOf('D')),
    athletic: !!(~this.genes.athletic.indexOf('D')),
    tall: !!(~this.genes.tall.indexOf('D'))
  };
}

// You don't have access to your own gene selection
// so we'll make this private (but in the javascript way)
Human.prototype._selectGenes = function (gene1, gene2) {
  // Assume that a gene is a 2 length array of the following possibilities
  // DD, Dr, rD, rr -- the latter being the only non "dominant" result

  // Simple random gene selection
  return [ gene1[Math.random() > 0.5 ? 1 : 0], gene2[Math.random() > 0.5 ? 1 : 0] ]
};

Human.prototype.sayHi = function () {
  console.log("Hello, I'm " + this.name);
};

function makeBaby(name, mother, father) {
  // Send in the genes of each parent
  var baby = new Human(name, mother.genes, father.genes);
  return baby;
}