为什么 React 中的 JavaScript 方法未定义？

Question

In this section, when I add the JavaScript method to my file, I get this error.

import './ExpenseItem.css';

function ExpenseItem(props) {
  const month = props.date.toLocaleString('en-US', { month: 'long' });
  const day = props.date.toLocaleString('en-US', { day: '2-digit' });
  const year = props.date.getFullYear();

  return (
    <div className='expense-item'>
      <div>
        <div>{month}</div>
        <div>{year}</div>
        <div>{day}</div>
      </div>
      <div className='expense-item__description'>
        <h2>{props.title}</h2>
        <div className='expense-item__price'>${props.amount}</div>
      </div>
    </div>
  );
}

export default ExpenseItem;

Answer 1

Native JavaScript method are available in React but it appears that you aren't passing date as a prop to ExpenseItem . You should have something like this in the parent component of ExpenseItem :

<ExpenseItem date={yourDateVariable}>