如何在http post中将图片从ionic发送到node.js？

import { Camera } from '@ionic-native/camera/ngx';
import { File } from '@ionic-native/file/ngx';
import { HttpClient } from '@angular/common/http';

constructor(private camera: Camera, private file: File, private http: HttpClient) {}

sendImageToNode() {
  this.camera.getPicture().then(imageData => {
    this.file.readAsDataURL(this.file.tempDirectory, imageData).then(base64Data => {
      const postData = {
        image: base64Data
      };
      this.http.post('http://your-node-server.com/upload', postData).subscribe(response => {
        console.log('Image uploaded successfully');
      }, error => {
        console.error('Failed to upload image');
      });
    });
  });
}

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

const app = express();

app.use(express.json());

app.post('/upload', (req, res) => {
  const base64Data = req.body.image.replace(/^data:image\/\w+;base64,/, '');
  const buffer = Buffer.from(base64Data, 'base64');
  fs.writeFile('uploaded_image.jpg', buffer, err => {
    if (err) {
      console.error('Failed to save image');
      res.status(500).send('Failed to save image');
    } else {
      console.log('Image saved successfully');
      res.send('Image saved successfully');
    }
  });
});

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