Javascript 我创建了一个创建对象的函数，我希望从该函数创建的对象具有唯一的键.我怎么能做到这一点

在pAequorFactory()中，当调用该函数来创建对象时.我希望.specimenNum对所有物体都是独一无二的.判断下面的代码

const pAequorFactory = (specimenNum, dna) => {
  return {
    specimenNum,
    dna,

    mutate() {
      randomBaseIndex = Math.floor[Math.random * 15];
      mutatedBase = returnRandBase();
      if (this.dna[randomBaseIndex] !== mutatedBase) {
        this.dna[randomBaseIndex] === mutatedBase;
        return this.dna;
      } else {
        mutate();
      }
    },

    compareDNA(object) {
      for (i = 0; i < 15; i++) {
        let j = 0;
        if (object.dna[i] === this.dna[i]) {
          j++;
        }
        let commonPercentage = (j / 15) * 100;
      }
      return `specimen #${this.specimenNum} and specimen #${object.specimenNum} have ${commonPercentage}% DNA in common`;
    },

    willLikelySurvive() {
      for (i = 0; i < 15; i++) {
        let j = 0;
        if (this.dna[i] === "C" || this.dna[i] === "G") {
          j++;
        }
        let survivePercentage = (j / 15) * 100;
      }
      return survivePercentage >= 60;
    },
  };
};

我还没有试过任何东西，但我正在想一种方法来比较每个物体的.specimenNum个.