main.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) => {
  let object = {
    number: specimenNum,
    DNA: dna,
    mutate() {
      const randomBase = Math.floor(Math.random() * dna.length);
      const removed = dna.remove(randomBase);
      const newBase = Math.floor(Math.random() * removed.length);
      return newBase;
    },
    compareDNA(pAequorObj) {
      let numOfCommon = 0;
      for (let i = 0; i < dna.length; i++) {
        if (pAequorObj.dna[i] === this.dna[i]) {
          numOfCommon += 1
        }
      };
      const percentage = (numOfCommon / 15 * 100).toFixed(2);
      return percentage;
      console.log(`Specimen 1 and Specimen 2 have ${percentage} DNA in common.`);
    },
    willLikelySurvive() {
      let cgBases = 0;
      for (let i = 0; i < this.DNA.length; i++) {
        if (this.DNA[i] === 'C' || this.DNA[i] === 'G') {
          cgBases += 1
        }
      };
      const sixtyPer = 15 / 10 * 6;
      return cgBases >= sixtyPer ? true : false
    }
  };
  return object
};

const create30 = () => {
  let pAequorArray = [];
  let i = 1;
  const newDNA = pAequorFactory(i, mockUpStrand());
  const surv = newDNA.willLikelySurvive();
  if (surv === true) {
    i += 1
    do {
      pAequorArray.push(newDNA);
    } while (pAequorArray.length < 30);
  }
  return pAequorArray
};


//test: 
// console.log(pAequorFactory(1, mockUpStrand()));

console.log(create30())

/* The result shows either empty array ([]) or something like this: 
[ { number: 1,
    DNA: [ 'G', 'T', 'T', 'C', 'T', 'G', 'C', 'C', 'G', 'C', 'C', 'G', 'A', 'T', 'A' ],
    mutate: [Function: mutate],
    compareDNA: [Function: compareDNA],
    willLikelySurvive: [Function: willLikelySurvive] }, ... ] ( 30 objects in total)
    
    I succeeded in printing out only 'surviving' DNAs using willLikelySurvive() function, but how can I get result with 
    amounting numbers for 'number' (my current result shows '1' for all objects), also, is it normal to just have 
    "mutate: [Function: mutate]" printed like that? Please help........
*/