Question

该计划的目的是随机创建15个DNA碱基的序列，然后能够根据要求更改此序列。这就是为什么您会发现2个有关随机DNA生成的功能，然后是带有变异方法的功能的原因。

不幸的是，console.log(dnaFactoried.mutate())一次返回undefined，范围为6。

这是我的代码：

// 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
}

// functionality of creation or mutation of the dna
const pAequorFactory = (number, dnaBase) => {
  return {
    specimenNum: number,
    dna: dnaBase(),
    mutate: function () {
      const random = Math.floor(Math.random()* this.dna.length);
      const toBeMutated = this.dna[random];
      const thatMutates = returnRandBase();
      if (toBeMutated == thatMutates) {
        this.mutate();
      } else {
        this.dna.splice(random, 1, thatMutates);
        return this.dna;
      } 
    }
  }
}
const dnaFactoried = pAequorFactory(1, mockUpStrand);
console.log(dnaFactoried.dna);
console.log(dnaFactoried.mutate());

Answer 1

您忘记在return this.mutate()上

if (toBeMutated == thatMutates) {      
  return this.mutate();   
}

否则，它仅返回undefined

// 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
}

// functionality of creation or mutation of the dna
const pAequorFactory = (number, dnaBase) => {
  return {
    specimenNum: number,
    dna: dnaBase(),
    mutate: function () {
      const random = Math.floor(Math.random()* this.dna.length);
      const toBeMutated = this.dna[random];
      const thatMutates = returnRandBase();
      if (toBeMutated == thatMutates) {
        return this.mutate();
      } else {
        this.dna.splice(random, 1, thatMutates);
        return this.dna;
      } 
    }
  }
}
const dnaFactoried = pAequorFactory(1, mockUpStrand);
console.log(dnaFactoried.dna);
console.log(dnaFactoried.mutate());

Answer 2

只需将return this.dna;移至if ... else语句之外。

JS函数返回未定义

2 个答案: