organisms.js

// Returns a random DNA base
const returnRandBase = () => {
  const dnaBases = ['A', 'T', 'C', 'G']
  return dnaBases[Math.floor(Math.random() * 4)] 
}

// Returns a random single stand of DNA containing 15 bases
const mockUpStrand = () => {
  const newStrand = []
  for (let i = 0; i < 15; i++) {
    newStrand.push(returnRandBase())
  }
  return newStrand
}

const pAequorFactory = (specimenNum, dna) => {
    return{
      specimenNum,
      dna,
      mutate() {
        const randIndex = Math.floor(Math.random() * this.dna.length);
        let newBase = returnRandBase();
        while (this.dna[randIndex] === newBase) {
          newBase = returnRandBase();
        } 
        this.dna[randIndex] = newBase;
        return this.dna;      
      },
      compareDna(otherOrg) {
        const similarities = this.dna.reduce((acc, curr, idx, arr) => {if (arr[idx] === otherOrg.dna[idx]) {
          return acc + 1;
        } else {
          return acc;
        }
        }, 0);
        const percentOfDNAshared = (similarities / this.dna.length) * 100;
        const percentageTo2Deci = percentOfDNAShared.toFixed(2);
        console.log(`${this.specimenNum} and ${otherOrg.specimenNum} have ${percentageTo2Deci}% DNA in common.`);
      },
      willLikelySurvive(){
        const cOrG = this.dna.filter(el => el === "C" || el === "G");
        return cOrG.length / this.dna.length >= 0.6;
      },    
    }
};

const survivingSpecimen = [];
let idCounter = 1;

while (survivingSpecimen.length < 30) {
  let newOrg = pAequorFactory(idCounter, mockUpStrand());
  if(newOrg.willLikelySurvive()) {
    survivingSpecimen.push(newOrg);
  }
  idCounter++;
}
console.log(survivingSpecimen)