使用React函数进行预览图像上传

import React, { useState } from 'react';

function ImageUploader() {
  const [previewImage, setPreviewImage] = useState(null);

  const handleImageChange = (event) => {
    const file = event.target.files[0];
    const reader = new FileReader();

    reader.onload = () => {
      setPreviewImage(reader.result);
    };

    if (file) {
      reader.readAsDataURL(file);
    }
  };

  return (
    <div>
      <input type="file" onChange={handleImageChange} />
      {previewImage && <img src={previewImage} alt="Preview" />}
    </div>
  );
}

function App() {
  return (
    <div>
      <h1>图像上传预览</h1>
      <ImageUploader />
    </div>
  );
}