如何使用angularJS2写入文件？

<input type="file" (change)="onFileSelected($event)">

onFileSelected(event: any) {
  const file: File = event.target.files[0];
  this.uploadFile(file);
}

import { HttpClient } from '@angular/common/http';

uploadFile(file: File) {
  const formData: FormData = new FormData();
  formData.append('file', file, file.name);

  this.http.post('/api/upload', formData)
    .subscribe(response => {
      console.log('File uploaded successfully');
    }, error => {
      console.error('Error uploading file:', error);
    });
}

const express = require('express');
const multer = require('multer');

const app = express();
const upload = multer({ dest: 'uploads/' });

app.post('/api/upload', upload.single('file'), (req, res) => {
  // 文件已保存在 req.file 中，可以进行文件写入操作
  // 例如：fs.writeFile(req.file.path, req.file.buffer, (err) => { ... });
  res.sendStatus(200);
});

app.listen(3000, () => {
  console.log('Server started on port 3000');
});