function formatNumber(number) {
  const regex = /(\d{1,4})(?=(\d{4})+$)/g;
  return number.toString().replace(regex, '$1 ');
}

import React, { useState } from 'react';

function App() {
  const [number, setNumber] = useState('');

  const handleChange = (event) => {
    const input = event.target.value.replace(/\s/g, ''); // 去除输入中的空格
    setNumber(formatNumber(input));
  };

  return (
    <div>
      <input type="text" value={number} onChange={handleChange} />
    </div>
  );
}

export default App;