這是我的前端我得到的變量的值interestRate，并monthlyPayment從API。我只想在前端設(shè)置這些值。這是我的代碼：class Display extends Component {componentDidMount() {    this.calculateAPR();  }  componentDidUpdate(prevProps) {      this.calculateAPR();    }  calculateAPR = () => {    let x = JSON.parse(localStorage.getItem('amount'));     a=x[0].amount;      t=x[0].years;    fetch("https://herokuapp.com/interest?amount="+a+"&numMonths="+t)      .then(res => res.json())      .then(        (result) => {          //console.log(result);          interestRate = result.interestRate;          monthlyPayment = result.monthlyPayment.amount;          console.log(interestRate, monthlyPayment);        },      )        this.calculateMonthlyRepayment(monthlyPayment);        this.percentageAPR(interestRate);  };  calculateMonthlyRepayment = (z) => {    return <p>${z}</p>;  };  percentageAPR = (z) => {    return <p>{z * 100}%</p>;  };  render() {    return (      <div className="flex">        <DisplayChild func={this.percentageAPR()} text="interest rate" />        <DisplayChild          func={this.calculateMonthlyRepayment()}          text=" monthly repayment"        />      </div>    );  }}這是我顯示這些值的地方，但這些值沒有顯示：const DisplayChild = ({ func, text }) => {  return (    <span>      {func} <small>{text}</small>    </span>  );};